Mode Of Distribution Research Articles

Study on the tensile properties of a novel modular splicing joint

The interconnection among module elements within a modular structure assumes a pivotal role in upholding structural integrity and stability. To address the challenges posed by existing inter-module connection joints, which necessitate operational space and may compromise the integrity of the module unit while impeding assembly efficiency, an innovative modular steel structure splicing joint is proposed. Through adjustments to the dimensions of the connection box and fastener components, four distinct spliced joints were established for axial tensile analysis. The subsequent evaluation included an examination of axial tensile capacity, strain distribution, and failure modes at critical points across various joints, providing insights into their tensile effectiveness. To comprehensively explore the influence of size parameters on tensile performance, a corresponding numerical model was developed for parametric analysis. Results indicate that tensile failure modes entail the extrication of the lower-end plate from the upper module column connection box and the cylindrical radius of the fastener. Notably, the protrusion radius of the fastener (R2), markedly influences the tensile bearing capacity of the spliced joints, with precedence over the lower end plate thickness (d0), cylinder radius (R1), sliding block thickness (d1), and limiting plate thickness (d2). The joint obviates the need for external operations to interlink module units, thereby augmenting the installation efficiency of the modular structure and mitigating complexities in design and the enigmatic transmission of forces within the self-locking joint.

Tensile performance prediction of CFRPs with voids using multiscale analysis and neural networks

The overall work provides a novel multiscale modeling strategy applicable to the mechanical response prediction of arbitrarily laid porous laminates under uniaxial tension by establishing representative defective volumes (RDVs) for the inter-ply and intra-ply regions. A representative defective volume modeling method based on void characterization results using X-ray computed tomography for the interlaminar region was proposed. Elastic properties, tensile strength, and fracture energies of porous and poreless microscale models were obtained and used in the macroscale model. Defective properties were assigned to partial elements in the macroscale model according to the preset distribution mode. The Extended Finite Element Method was taken to simulate the failure process. Tensile properties of porous laminates with stacking sequences of [90]8, [90/0/90/0]2S, and [45/90/-45/0]2S were experimentally tested and numerically simulated. The predicted tensile properties and crack propagation behavior coincide well with the test results. Besides, the effects of micro-voids and macroscopic void distribution were discussed in detail. Further, a back-propagation neural network was used to achieve a fast prediction of the tensile properties and save computational costs. The computation time (<1 s) greatly improved compared with multiscale modeling (>38 h). This work provides an efficient tool for composite performance prediction, design, and optimization.

Research on Express Crowdsourcing Task Allocation Considering Distribution Mode under Customer Classification

Research on Express Crowdsourcing Task Allocation Considering Distribution Mode under Customer Classification

Logistics distribution model and storage planning design based on multi-source information positioning in smart city development

The research mainly focuses on the inefficient planning of autonomous distribution and storage modes of distribution vehicles in smart city logistics and distribution, which in turn leads to poor customer experience, rising distribution costs, and wasted distribution resources. From the perspective of information processing in the logistics distribution process, the study takes multi-angle and multi-source information collection and fusion processing strategy as the main basis to help smart delivery robots realize map construction and autonomous positioning in the distribution process, and then facilitate real-time logistics distribution and storage mode planning by robots in combination with their own states. The research results show that the algorithm accuracy, standard error, and average running time of the extended Kalman filter localization model designed in the study are 0.96, 1.52, and 105s, respectively, with the algorithm accuracy being the highest and the other two values being the lowest in its class. Meanwhile, in the simulation logistics planning, the research-designed logistics planning model has the strongest information capturing ability, and the planning of distribution routes and storage modes is more reasonable, which can provide more efficient autonomous planning solutions.

Round-Trip Time Ranging to Wi-Fi Access Points Beats GNSS Localization

Wi-Fi round-trip time (RTT) ranging has proven successful in indoor localization. Here, it is shown to be useful outdoors as well—and more accurate than smartphone code-based GNSS when used near buildings with Wi-Fi access points (APs). A Bayesian grid with observation and transition models is used to update a probability distribution of the position of the user equipment (UE). The expected value (or the mode) of this probability distribution provides an estimate of the UE location. Localization of the UE using RTT ranging depends on knowing the locations of the Wi-Fi APs. Determining these positions from floor plans can be time-consuming, particularly when the APs may not be accessible (as is often the case in order to prevent unauthorized access to the network). An alternative is to invert the Bayesian grid method for locating the UE—which uses distance measurements from the UE to several APs with known position. In the inverted method we instead locate the AP using distance measurements from several known positions of the UE. In localization using RTT, at any given time, a decision has to be made as to which APs to range to, given that there is a cost associated with each “range probe” and that some APs may not respond. This can be problematic when the APs are not uniformly distributed. Without a suitable ranging strategy, one can enter a dead-end state where there is no response from any of the APs currently being ranged to. This is a particular concern when there are local clusters of APs that may “capture” the attention of the RTT app. To avoid this, a strategy is developed here that takes into account distance, signal strength, time since last “seen”, and the distribution of the directions to APs from the UE—plus a random contribution. We demonstrate the method in a situation where there are no line-of-sight (LOS) connections and where the APs are inaccessible. The localization accuracy achieved exceeds that of the smartphone code-based GNSS.

Failure analysis and structural resilience of a masonry arch Bridge subjected to blast loads: The Case study, Halilviran Bridge

This study investigates the dynamic response of masonry bridges under blast-induced shock waves, focusing on the structural integrity and safety of these critical infrastructure components under extreme conditions. The research employs theoretical approaches to analyze the effects of blast-induced shock waves on masonry bridge structures. A comprehensive numerical simulation framework is developed using finite element analysis (FEA) to model the dynamic interactions between blast waves and the masonry materials. Key parameters, including the blast load intensity, duration, and distance from the blast source, are varied to assess their impact on bridge performance. The results reveal significant insights into the deformation patterns, stress distribution, and potential failure modes of masonry bridges under blast loading scenarios. The findings underscore the importance of incorporating blast resistance measures in the design and retrofitting of masonry bridges to enhance their resilience against explosive events. This study contributes to the advancement of safety standards and design guidelines for masonry bridge structures in the context of blast loading, providing valuable information for engineers, policymakers, and infrastructure managers.

Analysis of the Spatial Distribution and Common Mode Error Correlation in a Small-Scale GNSS Network.

When analyzing GPS time series, common mode errors (CME) often obscure the actual crustal movement signals, leading to deviations in the velocity estimates of station coordinates. Therefore, mitigating the impact of CME on station positioning accuracy is crucial to ensuring the precision and reliability of GNSS time series. The current approach to separating CME mainly uses signal filtering methods to decompose the residuals of the observation network into multiple signals, from which the signals corresponding to CME are identified and separated. However, this method overlooks the spatial correlation of the stations. In this paper, we improved the Independent Component Analysis (ICA) method by introducing correlation coefficients as weighting factors, allowing for more accurate emphasis or attenuation of the contributions of the GNSS network's spatial distribution during the ICA process. The results show that the improved Weighted Independent Component Analysis (WICA) method can reduce the root mean square (RMS) of the coordinate time series by an average of 27.96%, 15.23%, and 28.33% in the E, N, and U components, respectively. Compared to the ICA method, considering the spatial distribution correlation of stations, the improved WICA method shows enhancements of 12.53%, 3.70%, and 8.97% in the E, N, and U directions, respectively. This demonstrates the effectiveness of the WICA method in separating CMEs and provides a new algorithmic approach for CME separation methods.

Satire vs Sentiment: Mark Twain, Bella Z. Spencer, and the Subscription Book Market

Abstract: This essay argues that Mark Twain has been overrepresented in scholarship on subscription bookselling, resulting in a corresponding failure to account for fiction's relationship to this popular nineteenth-century practice. Though Twain's The Gilded Age (1873) is often described as the first novel sold by subscription, I recover an earlier example: Tried and True (1866), a Civil War romance by Bella Zilfa Spencer. Reading the novel's mode of distribution as integral to its treatment of gender, race, and geography, I demonstrate the potential for literary study which gets lost somewhere between subscription bookselling's bad reputation and Mark Twain's good one.

Numerical simulation to influence of fluid distribution on acoustic attenuation coefficient in gas water two-phase fractured media

Abstract The equivalent fluid model simplifies the actual distribution state of fluid, and the relationship between rock elastic properties and pore fluid parameters established by the equivalent fluid model usually deviates greatly from the experimental results. A random discrete fracture model is established, and the gas-water two-phase distribution in fracture pores is described in detail. Based on the acoustic wave theory, the finite difference numerical simulation of the acoustic wave field of the rock sample model is carried out. The variation law of acoustic attenuation coefficient with saturation under the different pore fluid distribution modes is analyzed. It is of great significance to the prediction of rock pore structure and the identification of reservoir fluid.

Participation of wind-storage combined system in the secondary frequency regulation control strategy of power grid

Abstract The secondary frequency modulation of the unit, that is, the automatic generation control (AGC), is the process of increasing or decreasing the power of the power generation unit by the power plant unit according to the dispatching command issued by the power grid dispatching center, and then using the frequency modulator to restore the frequency. Based on the principle of AGC, this paper establishes a frequency dynamic response model of the secondary frequency modulation of the traditional unit and the wind storage participation system including load frequency control (LFC) and traditional proportional-integral-derivative (PID) controllers, determines the frequency modulation control strategy of wind storage, and uses the distribution mode based on Area Control Error (ACE) signal to assist in the secondary frequency modulation. In order to solve the parameter optimization problem of the classical PID controller when the wind-storage combined system participates in the secondary frequency modulation under the large load disturbance, a parameter optimization model of the controller with PID was established, and the ITAE evaluation index was finally selected as the fitness function by comparing different fitness evaluation indexes. To overcome the problem that the conventional Particle Swarm Optimization (PSO) is prone to local extremum, the inertia weights and learning factors are adjusted nonlinearly to balance and optimize the global and local optimization capabilities and improve the search efficiency, and the parameters of the PID controller are optimized by the improved PSO algorithm. The simulation results show that the proposed algorithm improves the secondary frequency modulation effect under the background of a high proportion of renewable energy connected to the power grid.

Distribution strategy of flexible phase change materials for pouch battery thermal management considering temperature non-uniformity

Flexible composite phase change materials (CPCMs) have been extensively studied in the thermal management of cylindrical lithium-ion batteries and proven to have a good cooling effect. However, passive cooling of pouch lithium-ion batteries with severe uneven temperature distribution has not received the attention it deserves. The thermal management of pouch battery based on passive cooling of flexible PCMs considering the heat-generating structure of pouch batteries needs to be further studied. Herein, CPCMs with different thermal conductivity were prepared, and four different distribution modes of CPCMs, including partial coverage and complete coverage, were applied to thermal management of pouch battery. Results indicated that the maximum temperature (Tmax) and maximum temperature difference (ΔTmax) can be kept separately within 35 °C and 5 °C in the passive thermal management of a single battery except upper coverage at discharge rate of 5C, and the middle coverage (case B) showed excellent temperature control in partial coverage cases. Equally noteworthy was that the increase in thermal conductivity increased the ΔTmax in partial coverage cases, while showing the opposite trend for full coverage (case ABC). Furthermore, only passive cooling of pouch battery pack did not meet the safety requirements under the discharge rate cycle of 5C. Under the active–passive combination mode, case B can control the Tmax (32.22 °C) and ΔTmax (4.69 °C) within a safe range, which was superior to case ABC (Tmax = 35.53 °C, ΔTmax = 5.04 °C). This conclusion provides technical support for the pouch battery to seek economic, stable and efficient thermal management.

Confinement-Driven Dimethyl Ether Carbonylation in Mordenite Zeolite as an Ultramicroscopic Reactor.

ConspectusThe conversion of C1 molecules to methyl acetate through the carbonylation of dimethyl ether in mordenite zeolite is an appealing reaction and a crucial step in the industrial coal-to-ethanol process. Mordenite zeolite has large 12-membered-ring (12MR) channels (7.0 × 6.5 Å2) and small 8MR channels (5.7 × 2.6 Å2) connected by a side pocket (4.8 × 3.4 Å2), and this unique pore architecture supplies its high catalytic activity to the key step of carbonylation. However, the reaction mechanism of carbonylation in mordenite zeolite is not thoroughly established in that it is able to explain all experimental phenomena and improve its industrial applications, and the classical potential energy surface exerted by static density function theory calculations cannot reflect the reaction kinetics under realistic conditions because the diffusion kinetics of bulk DME (kinetic dimeter: 4.5 Å) and methyl acetate (MA, kinetic dimeter: 5.5 Å) were not well considered and their restricted diffusion in the narrow side pocket and 8MR channels may greatly alter the integrated kinetics of DME carbonylation in mordenite zeolite. Moreover, the precise illustration of the dynamic behaviors of the ketene intermediate and its derivatives (surface acetate and acylium ion) confined within various voids in mordenite has not been effectively portrayed.Advanced ab initio molecular dynamics (AIMD) simulations with or without the acceleration of enhanced sampling methods provide tremendous opportunities for operando modeling of both reaction and diffusion processes and further identify the geometrical structure and chemical properties of the reactants, intermediates, and products in the different confined voids of mordenite under realistic reaction conditions, which enables high consistency between computations and experiments.In this Account, the carbonylation process in mordenite is comprehensively described by the results of decades of continuous research and newly acquired knowledge from both multiscale simulations and in-(ex-)situ spectroscopic experiments. Three primary steps (DME demethylation to surface methoxy species (SMS), carbon-carbon bond coupling between SMS and CO to acetyl species, and methyl acetate formation by acetyl species and methanol/DME) have been respectively studied with a careful consideration of different molecular factors (reactant distribution, concentration, and attack mode). By utilizing the free-energy surface of diffusion and reaction obtained from AIMD simulations, a comprehensive reaction/diffusion kinetic model was formulated for the first time, illustrating the entire zeolite catalytic process. In this context, a comprehensive and informative analysis of the reaction kinetics of carbonylation in mordenite, including the function of the 12MR channels, 8MR channels, and side pockets in the adsorption, diffusion, and reaction of DME carbonylation, was performed. The different channels of mordenite play different roles in all ordered reaction steps, illustrating a highly organized ultramicroscopic reactor that is encompassed.

Delay-Optimized Edge Caching in Integrated Satellite–Terrestrial Networks With Diverse Content Popularity Distribution and User Access Modes

Delay-Optimized Edge Caching in Integrated Satellite–Terrestrial Networks With Diverse Content Popularity Distribution and User Access Modes

A Review of Research on Cold Chain Logistics and Distribution of Fresh Agricultural Products in China

At present, China, as the second largest economy in the world, is in the new development pattern, that is, to build a new development pattern with the domestic macro-cycle as the main body and the domestic and international double-cycle promoting each other, which has high requirements for the smoothness of the circulation system, urgently needs the circulation system to have a high degree of smoothness, and urgently needs to accelerate the upgrading of the logistics distribution industry, so as to realise the synchronous development of the logistics distribution industry and the economy of the country. Moreover, under the background of China's rapid development, people's needs for fresh agricultural products and other cold-chain products, as well as product quality requirements have gradually improved, therefore, under the background of rapid changes in the market, the management of China's cold-chain logistics should also be further improved to meet the market requirements. Based on this, this paper takes cold chain logistics and distribution as an entry point, and through the current development status of cold chain logistics and distribution of fresh agricultural products, the distribution mode status quo, the current research status of the constraints of fresh agricultural products logistics and distribution, as well as distribution optimisation strategy research, etc., it is hoped to draw the research direction and research focus of future cold chain logistics and distribution of fresh agricultural products, with a view to providing reference opinions to promote China's fresh agricultural products in the cold chain logistics development and improvement, so as to meet the market's requirements. In order to provide reference opinions to promote the development and improvement of the cold chain logistics of fresh agricultural products in China, so as to meet the higher requirements of the people for fresh agricultural products.

Parasite transmission stage abundance varies in lakes over time and space

AbstractEnvironmentally transmitted parasites produce transmission stages that can remain viable and infective for extended periods of time in the environment where susceptible hosts may encounter them. Although many parasites have this mode of transmission, the abundance and distribution of environmental transmission stages have largely been overlooked, especially in aquatic habitats. Without empirical data to characterize spatial and temporal dynamics of parasite transmission stages in the environment, we might make incorrect assumptions about host–parasite contact rates. For aquatic environments, seasonal habitat structure driven by thermal stratification has been hypothesized to affect the patchiness of transmission stages within the water column, leading to uneven exposure risk to hosts. In this study, we quantified transmission stage concentrations of five common parasites of Daphnia spp. and Ceriodaphnia dubia at every meter of the water column at the deep basin of six lakes in southeastern Michigan every 2 weeks from June to November 2021. We found that transmission stage concentration varied by orders of magnitude over time and with depth. We investigated several possible drivers of these spatial and temporal patterns. For instance, our results suggest that greater mixing depth decreased transmission stage vertical patchiness within the water column of lakes with lower Fee's p values. However, horizontal spore patchiness across a lake was not correlated with the nearshore–offshore gradient of our study lakes. Overall, the results of our study show that parasite transmission stage concentrations have spatial and temporal dynamics that could affect disease dynamics within highly structured aquatic environments.

4D printing bio-inspired chiral metamaterials for flexible sensors

Chiral metamaterials were a typical metamaterial configuration, which had broad application prospects in vibration isolation, energy absorption and other fields. Although 4D-printed chiral metamaterials have been investigated by introducing stimulus-responsive materials to achieve programmable properties of metamaterials, chiral metamaterials are mostly fabricated by single materials, which limits the adjustable domains of the mechanical properties and the design freedom of metamaterials. In this work, inspired by the configuration of collagen fibers of biological tissues, the bio-inspired chiral metamaterials with wave ligaments were developed. The bi-phase (TPE@PLA-SMP) composite chiral metamaterials were fabricated by combining active phase (shape memory polylactic acid, PLA-SMP) with passive phase (thermoplastic elastomer, TPE). The influences of geometric parameters, ligament gradient forms, and TPE distribution modes on the mechanical properties of the developed metamaterials were characterized. When the TPE was distributed at 0° and 45°, the deformation of the mechanical metamaterials occurred mainly in the TPE cells, resulting in the J-shaped displacement-force curve. The programmable and reconfigurable properties of the metamaterials (including configuration, and energy absorption performance) under thermal stimulation were demonstrated. The specific energy absorption (SEA) of the metamaterial 2θ = π/2 was realized to transform between 0.92 kJ/kg and 0.38 kJ/kg by shape memory programming. Flexible sensors based on TPE@PLA-SMP composite metamaterials were developed by filling CNC-CNT@PVA composite hydrogels (minimum resistivity 8.1 Ω m), which enabled stable output of electrical signals under repeated loads. A motion state monitor was developed and realized to monitor the wearer's movement such as running, demonstrating its potential application prospects in fields such as flexible electronics.

A dynamics simulation-assisted transfer learning method for track condition diagnosis in urban rail transits

Track defects are gradually emerging with the development of urban rail transits. However, there is rare research implemented to diagnose track conditions in real time. Although some intelligent data-driven methods seem to have the potential to achieve the track condition diagnosis, it’s hard to acquire sufficient labeled data in actual applications. This study proposes a dynamics simulation-assisted transfer learning (TL) method for label-scarce track condition diagnosis. Firstly, a dynamics model of axle-box bearings considering the service environment is established. Based on this model, a large amount of axle-box vibration signals corresponding to healthy/defective track conditions is simulated. Wavelet transform is performed for these signals to characterize their time-frequency energy distribution modes in the format of time-frequency maps, which are considered source-domain data. Similarly, the time-frequency maps of the collected signals during vehicle operation are served as the target-domain data. Subsequently, a sub-domain alignment TL network is constructed to map the data from the source and target domain into a deep feature space. In this network, unlabeled target-domain data are classified to obtain their pseudo labels. Finally, Wasserstein distance measure and multiple domain discriminators are employed to achieve label alignment between two domains for each corresponding category. A feature centroid-driven loss function is applied to further reduce the intra-class variations, ultimately realizing accurate knowledge transfer from simulated signals to collected signals. A two-level sliding window algorithm is designed to detect abnormal axle-box vibration signal parts which are then diagnosed through the well-trained network. The proposed method is validated through a transfer diagnosis experiment using simulated signals and collected signals. This study provides a promising solution to diagnose different track conditions, which is of great significance for ensuring running safety in urban rail transits.

Effects of exhalation modes and spatial distribution of an infected person on contaminant transmission in a classroom

Classrooms pose a huge risk from the cross-infection of respiratory infections. However, quantitative research on the combined effect of the location of the infected individual and exhalation activities on the diffusion and dissemination of contaminants in a classroom is lacking. We elucidated the effects of spatial distribution and exhalation modes of infected individuals, especially when they talk and breath nasally, on dissemination of contaminants under different ventilation modes: mixing (MV) and stratum ventilation (SV), using computational fluid dynamics, and calculated the contaminant removal efficiency (CRE) and personnel infection time (tin). Infected individuals’ exhalation modes and spatial distribution significantly affected indoor exposure risk. Under SV, risk was low (tin > 0.75 h) when infected individuals talk, but significantly higher (tin ≤ 0.75 h) during nasal exhalation. In MV, risk was lower (tin > 0.75 h) when infected individuals were near the outlet, but increased (tin ≤ 0.75 h) when they were further away. CRE revealed that MV was more sensitive to location changes (12.4- and 5.8-fold) than to exhalation mode changes (2.1- and 0.99-fold). Conversely, SV was more sensitive to exhalation mode changes (5.7- and 2.8-fold) than to location changes (3.7- and 1.8-fold), emphasizing the importance of the distribution of infected individuals and exhalation modes in classroom ventilation design.

An inerter-enhanced bistable nonlinear energy sink for seismic response control of building structures

Structural control strategies have attracted great attention in reducing unwanted structural responses. To mitigate the vibrations of seismically excited buildings, this paper proposes a novel vibration control device: an inerter-enhanced bistable nonlinear energy sink (BNESI). A three-story building structure is selected as an example, where the BNESI is attached to the top of the structure and linked to the top second floor of the structure, to explore the control effect of the device under earthquakes. The restoring force of the BNESI and equations of motion for the BNESI-controlled system are derived first. Subsequently, a multi-objective optimization design method of the BNESI is proposed and applied in building structures. The input energy robustness of the BNESI is then accessed by various initial velocities subjected to the structures. Moreover, the seismic vibration mitigation capacity of the BNESI is systematically investigated under a group of near-field and far-field excitations. Analysis results show that the proposed design algorithm for BNESI can be an attractive alternative to effectively obtain optimal parameters of the control device. The BNESI is less sensitive to the input energy levels, and can stably capture and dissipate energy from the primary structure. Also, the BNESI system provides good control effectiveness with less sensitivity to the uncertainty of seismic excitations. In addition, with less standard deviation, the damper stroke of the BNESI is only about a quarter of that of the TMD under the same excitation. Moreover, the damage to the primary structure has a negligible effect on the control effect of the BNESI system. Meanwhile, the BNESI can decrease the energy dissipation demand on the structure, and the energy distribution mode of the BNESI system shows less sensitivity to the frequency decrease of the structure.

Bubble 36Ar and its new breathing modes

The bubble nuclei are important components of exotic nuclear structures characterized by special depletions of central densities. Focusing on bubble structures of 36Ar, the characterizations of bubble nuclei were explored with the framework of the extended quantum molecular dynamics model. Three density distribution modes were uncovered for the first time, i.e. micro-bubble, bubble, and cluster resonances, which show unique spectral signature compared to the monopole resonance spectrum as the excitation intensity was increased in bubbles. Of pivotal importance is the revelation that the bubble mode's oscillation frequency closely resembles macroscopic bubble dynamics, building a connection between classical macroscopic phenomena and the quantum complexity of the nuclear structure. The discovery marks a crucial step forward in deciphering the relationship between classical and quantum domains within the enigmatic world of atomic nuclei.