Effect Of Buffer Size Research Articles

Deadlock control and hybrid social spider scheduling algorithm for two-stage assembly permutation flowshop with limited buffers

This paper focuses on the deadlock control and scheduling problem of two-stage assembly permutation flowshop with limited buffers. In such a system, all parts are first processed in a permutation flowshop, then assembled into final products. The objective is to find a feasible schedule, including a manufacturing subschedule and an assembly subschedule, to minimize makespan. Owing to limited buffers, not only may the blocking phenomenon appear in the system operation, but also some manufacturing subschedules may lead to deadlock states, making them unavailable. To obtain a feasible schedule, this work first proposes a deadlock control or an availability detection and amendment (ADA) algorithm to determine whether a manufacturing subschedule is available, and convert unavailable ones to available ones. Then by embedding ADA into a social spider algorithm (SSA), a hybrid social spider algorithm (HSSA) is developed for computing feasible schedules. In HSSA, an improved heuristic search algorithm is proposed to generate a better initial population, and a simplified variable neighborhood search algorithm is designed and incorporated into HSSA to enhance its searching ability. Finally, HSSA is tested on instances, showing its superiority over SSA in performance. The effect of buffer size on the scheduling objective is discussed.

Effects of buffer size on associations between the built environment and metro ridership: A machine learning-based sensitive analysis

Uncertainty in the relevant buffer size of metro station catchment areas may drive inconsistencies in the findings on the built environment and metro ridership. Although previous studies estimate the effect of this uncertainty, the results are far from definitive. By utilizing finer-grained big data and non-parametric machine learning approaches, this study conducted a sensitivity analysis defining built environment factors within four radial buffer sizes: 300 m, 600 m, 800 m, and 1000 m on associations with metro ridership. The results suggest that: (1) different buffer sizes have little influence on the ordinary least-squares model's predictive power, but significant influence on the machine learning model; (2) the use of a 600 m buffer size around the transit station demonstrates the best model fit and variation explanation compared to others; (3) findings on the relative importance, ranks, and nonlinear associations with metro ridership can be impacted as the choice of geographic delineation of buffer sizes deviate from the true relevant geographic context of built environment variables. The results assist planners in setting a benchmark for metro catchment areas for station-area planning and demand forecasting, more importantly, the findings highlight the importance of meticulously selecting the analytical spatial unit for area-based variables, especially when utilizing non-parametric machine learning approaches in research.

Effects of Buffer Size and Shape on the Association of Neighborhood SES and Adult Fruit and Vegetable Consumption.

Introduction: Neighborhood environment factors are relevant for dietary behaviors, but associations between home neighborhood context and disease prevention behaviors vary depending on the definition of neighborhood. The present study uses a publicly available dataset to examine whether associations between neighborhood socioeconomic status (NSES) and fruit/vegetable (FV) consumption vary when NSES is defined by different neighborhood sizes and shapes.Methods: We analyzed data from 1,736 adults with data in GeoFLASHE, a geospatial extension of the National Cancer Institute's Family Life, Activity, Sun, Health, and Eating Study (FLASHE). We examined correlations of NSES values across neighborhood buffer shapes (circular or street network) and sizes (ranging from 400 to 1,200 m) and ran weighted simple and multivariable regressions modeling frequency of FV consumption by NSES for each neighborhood definition. Regressions were also stratified by gender.Results: NSES measures were highly correlated across various neighborhood buffer definitions. In models adjusted for socio-demographics, circular buffers of all sizes and street buffers 750 m and larger were significantly associated with FV consumption frequency for women only.Conclusion: NSES may be particularly relevant for women's FV consumption, and further research can examine whether these associations are explained by access to food stores, food shopping behavior, and/or psychosocial variables. Although different NSES buffers are highly correlated, researchers should conceptually determine spatial areas a priori.

The Effects of GPS-Based Buffer Size on the Association between Travel Modes and Environmental Contexts

To investigate the association between physical activity (including active travel modes) and environmental factors, much research has estimated contextual influences based on zones or areas delineated with buffer analysis. However, few studies to date have examined the effects of different buffer sizes on estimates of individuals’ dynamic exposures along their daily trips recorded as GPS trajectories. Thus, using a 7-day GPS dataset collected in the Chicago Regional Household Travel Inventory (CRHTI) Survey, this study addresses the methodological issue of how the associations between environmental contexts and active travel modes (ATMs) as a subset of physical activity vary with GPS-based buffer size. The results indicate that buffer size influences such associations and the significance levels of the seven environmental factors selected as predictors. Further, the findings on the effects of buffer size on such associations and the significance levels are clearly different between the ATMs of walking and biking. Such evidence of the existence of buffer-size effects for multiple environmental factors not only confirms the importance of the uncertain geographic context problem (UGCoP) but provides a resounding cautionary note to all future research on human mobility involving individuals’ GPS trajectories, including studies on physical activity and travel behaviors, especially on the reliable estimation of individual exposures to environmental factors and their health outcomes.

Analysis of tandem polling queues with finite buffers

We analyze a tandem polling queue with two stations operating under three different polling strategies, namely: (1) Independent polling, (2) Synchronous polling, and (3) Out-of-sync polling. Under Markovian assumptions of arrival and service times, we conduct an exact analysis using Matrix Geometric method to determine system throughput, mean queue lengths, and mean waiting times. Through numerical experiments, we compare the performance of the three polling strategies and the effect of buffer sizes on performance. We observe that the independent polling strategy generally performs better than the other strategies, however, under certain settings of product asymmetry, other strategies yield better performance.

Influence of digital terrain model on mapping of slope deposits depth

In this work the influence of the characteristics of different Digital Terrain Models (DTMs) on Slope Deposits depth (dSD) maps is evaluated. dSD data collected during fieldwork have been mapped through GPS. Two different DTMs have been used for the analysis: one derived from LiDAR survey (1 m pixel size), the other extracted by the topographic maps of Regione Toscana (10 m pixel size). dSD maps have been extracted by integrating cluster analysis of morphometric variables with dSD data. In order to investigate the effects of spatial resolution, the LiDAR DTM has been down-sampled to both 5 m and 10 m. The weight of GPS positioning uncertainty has been assessed by performing a statistical analysis on the morphometric clusters falling into buffer areas of sampling points. Comparisons among outputs have been performed through map accuracy estimations, as well as by spatial distribution visual check and extension assessment of dSD classes. Results show that by increasing spatial resolution of input DTMs the statistical quality of the dSD maps generally reduces. Concerning the effect of buffer size around sampling points, as a general rule, the larger the buffer, the lower the map accuracy. Only the map obtained by 1 m LiDAR DTM is insensitive to buffer size.

Generating max-plus equations for efficient analysis of manufacturing flow lines

An elegant mathematical tool, max-plus algebra, can be used to model manufacturing flow lines in the form of linear state-space-like equations for application in manufacturing systems analysis and control. A method for quick and efficient generation of the max-plus equations for manufacturing flow lines of any size or structure has been developed. The generated equations are used to model flow lines with finite buffers between stations as well as parallel identical stations.A flow line is initially assumed to have infinite buffers for all stations and no parallel identical stations. An adjacency matrix is then used to encode the layout of the flow line and determine the relationships between different stations in the line. The max-plus equations for the line are then generated for the simplified line while capturing the line dynamics in two matrices that are function of the processing times of the different stations in the line. Additional terms are used to model finite buffers and the parallel identical stations.The developed manufacturing systems modelling method using max-plus algebra is intuitive and easy to understand and code in software. It is a decision support tool which facilitates quick analysis of different configurations of manufacturing flow lines and assessment of several what-if scenarios. A case study is presented where the max-plus equations are generated for three possible assembly line configurations for a back flushing control valve. The effect of buffer sizes and changes in the assembly time of one of the stations on the total line idle time is analyzed using the generated model.

Effects of buffer size and shape on associations between the built environment and energy balance

Uncertainty in the relevant spatial context may drive heterogeneity in findings on the built environment and energy balance. To estimate the effect of this uncertainty, we conducted a sensitivity analysis defining intersection and business densities and counts within different buffer sizes and shapes on associations with self-reported walking and body mass index. Linear regression results indicated that the scale and shape of buffers influenced study results and may partly explain the inconsistent findings in the built environment and energy balance literature.

An improved particle swarm optimisation with a linearly decreasing disturbance term for flow shop scheduling with limited buffers

The flow shop scheduling problem with limited buffers is a typical combinational optimisation problem that is NP-hard. In this article, an improved particle swarm optimisation with a linearly decreasing disturbance term (LDPSO) is presented for permutation flow shop scheduling with limited buffers between consecutive machines to minimise the maximum completion time (i.e. the makespan). A linearly decreasing disturbance term was added to the velocity, updating formula of the standard particle swarm optimisation algorithm. The decision probability of the linearly decreasing disturbance term was used to control the utilisation of the global exploration operation and the local exploitation search based on problem-specific information so as to prevent premature convergence and concentrate computing efforts on promising neighbour solutions. Theoretical analysis based on previous studies showed that the improved algorithm converged to the global optimum at a probability of 1. The ranked-order-value encoded method transferred the continuous particle position of the LDPSO to the order sequence. Furthermore, the neighbour search strategy based on block guaranteed that the entire order sequence could be searched. Simulation results and comparisons based on benchmarks demonstrate the effectiveness of the LDPSO. The effects of buffer size and decision probability on optimisation performance are discussed in this article.

Effect of Buffer Size around Nanosilicon Anode Particles for Lithium-Ion Batteries

Si nanoparticle/carbon composites in which each Si nanoparticle was embedded in a spherical nanospace were synthesized by a newly established hard-template pathway. A series of composites having different nanospace sizes were prepared, and their lithium insertion/extraction behaviors as an anode for lithium-ion batteries were examined. The nanospace which surrounds each Si nanoparticle can be a buffer against the Si expansion during its lithiation. By using the series of composites, the effect of the buffer size around nanosilicon was systematically investigated. The cyclability became better with increasing the buffer size up to about 3 times larger than the Si volume, i.e., the size which allows Si to expand up to 4 times larger than its original volume. Indeed, the structure of the porous carbon matrix was well retained even after 20 charge–discharge cycles in the Si/carbon composite with this appropriate buffer size, whereas a composite with a smaller buffer size was totally destroyed. The further inc...

An effective hybrid genetic algorithm for flow shop scheduling with limited buffers

As a typical manufacturing and scheduling problem with strong industrial background, flow shop scheduling with limited buffers has gained wide attention both in academic and engineering fields. With the objective to minimize the total completion time (or makespan), such an issue is very hard to solve effectively due to the NP-hardness and the constraint on the intermediate buffer. In this paper, an effective hybrid genetic algorithm (HGA) is proposed for permutation flow shop scheduling with limited buffers. In the HGA, not only multiple genetic operators based on evolutionary mechanism are used simultaneously in hybrid sense, but also a neighborhood structure based on graph model is employed to enhance the local search, so that the exploration and exploitation abilities can be well balanced. Moreover, a decision probability is used to control the utilization of genetic mutation operation and local search based on problem-specific information so as to prevent the premature convergence and concentrate computing effort on promising neighbor solutions. Simulation results and comparisons based on benchmarks demonstrate the effectiveness of the HGA. Meanwhile, the effects of buffer size and decision probability on optimization performances are discussed.

Performance study of buffering within switches in LANs

Today's demanding applications, such as multimedia, require higher network transfer rates. Traditional LANs will not be able to provide the throughput required by these applications. The use of switches in LANs is an effective technique to increase the throughput of the network. These switches have finite buffers at their input and output ports. The size of these buffers affect the packet loss rate. It also affects the delay at the switch, as packets may have to wait for the output buffer to become available. In this paper, we study the effect of buffer sizes within these switches. We show how the buffer size is related to the performance of the switch, as well as overall performance of the LAN.

A performance model of pipelined k-ary n-cubes

Pipelined communication using virtual channels can realize low latency, high throughput, inter-processor communication. This paper presents an analytic performance model of pipelined communication in k-ary n cubes. The model contains elements intended to capture and study key performance issues. In addition to the modeling of throughput and latency, the following issues are addressed using this model: (1) the tradeoff between full-duplex vs. half-duplex links, (2) the effects of intranode delay, (3) the effects of buffer size for each virtual channel. Detailed simulation experiments under a variety of conditions establish the viability of this model. >

The effect of buffer size on pages accessed in random files

Prior works, for estimating the number of pages (blocks) accessed from secondary memory to retrieve a certain number of records for a query, have ignored the effect of main memory buffer size. While this may not cause any adverse impact for special cases, in most cases the impact of buffer sizes will be to increase the number of page accesses. This paper describes the reasons for the impact due to a limited buffer size and develops new expressions for the number of pages accessed. The accuracy of the expressions is evaluated by simulation modeling; and the effects of limited buffer size are discussed. Analytical works in database analysis and design should use the new expressions: especially when the effect of the buffer size is significant.