Buffer Level Research Articles

Unpaced Merging Lines With Uneven Buffer Allocation

As a common production practice in many developing economies and in reverse logistics, unbalanced merging assembly lines are a research area which is re-emerging in prominence. This paper aims to study the performance of reliable, unpaced merging assembly lines that are unbalanced in terms of their buffer storage sizes. Lines are simulated with different values of line length, mean buffer storage capacity and configuration of uneven buffer allocation. The best patterns in terms of generating higher throughput and lower average buffer level as compared to a balanced merging line are those where total available buffer capacity is allocated as evenly as possible between workstations and to concentrate more buffer capacity towards the end of the line, respectively.

On the trajectory of video quality transition in HTTP adaptive video streaming

HTTP adaptive video streaming matches video quality to the capacity of a changing context. A variety of schemes that rely on buffer state dynamics for video rate selection have been proposed. However, these schemes are predominantly based on heuristics, and appropriate models describing the relationship between video rate and buffer levels have not received sufficient attention. In this paper, we present a QoE-aware video rate evolution model based on buffer state changes. The scheme is evaluated within a real-world Internet environment. The results of an extensive evaluation show an improvement in the stability, average video rate and system utilisation, while at the same time a reduction in the start-up delay and convergence time is achieved by the modified players.

Discrimination-related Anger, Religion, and Distress: Differences between African Americans and Caribbean Black Americans

The Charleston Emanuel African Methodist Episcopal Church (AMEC) survivors’ forgiveness of the racially motivated shootings prompted our research of the association between religion, discrimination-related anger, and psychological distress among black Americans. Using the first representative national sample of Caribbean black Americans, the National Survey of American Life, we examine if discrimination-related anger produces more psychological distress for African Americans than Caribbean black Americans and if religious emotional support lowers distress from discrimination-related anger. Our findings show discrimination-related anger is associated with less distress for Caribbean black Americans than African Americans. Religious emotional support is associated with lower levels of distress and buffers the mental health of later generation Caribbean black Americans who report anger. African Americans reporting discrimination without anger show lower levels of psychological distress than their counterparts who experience anger. Thus, we have partial support that mercy towards one’s transgressor, illustrated by the Charleston Emanuel AMEC survivors, may benefit mental health.

Developmental graphemic buffer dysgraphia in English: A single case study

ABSTRACTA single case study is reported of a 10-year-old, English-speaking boy, L.S., who presented with spelling errors similar to those described in acquired graphemic buffer dysgraphia (GBD). We used this case to evaluate the appropriateness of applying adult cognitive models to the investigation of developmental cognitive disorders. The dual-route model of spelling guided this investigation. L.S. primarily made “letter errors” (deletions, additions, substitutions, transpositions, or a combination of these errors) on words and nonwords and in all input (aural and visual) and output modalities (writing, typing, oral spelling); there was also some evidence of a length effect and U-shaped serial position curve. An effect of lexical variables on spelling performance was also found. We conclude that the most parsimonious account is an impairment at the level of the graphemic buffer and without systematic cognitive neuropsychological investigation, the nature of L.S.’s spelling difficulty would likely have been missed.

Presymptomatically applied AMPA receptor antagonist prevents calcium increase in vulnerable type of motor axon terminals of mice modeling amyotrophic lateral sclerosis

Increased intracellular calcium (Ca), which might be the consequence of an excess influx through Ca-permeable α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors, plays a crucial role in degeneration of motor neurons. Previously we demonstrated that the presymptomatic application of AMPA receptor antagonist, talampanel, could reduce Ca elevation in spinal motor neurons of mice carrying the G93A mutation of superoxide dismutase 1 (SOD1), modeling amyotrophic lateral sclerosis (ALS). It remained to be examined whether the remote, functionally semi-autonomous motor axon terminals could be rescued from the Ca overload, or if the terminals, where the degeneration possibly starts, already experience intractable changes at early time points. Thus using electron microscopic techniques, we measured the Ca level of motor axon terminals in the interosseus muscle of the SOD1 mutant animals, which are prototypes of vulnerable nerve endings in ALS. In line with the results obtained in the perikarya, talampanel treatment could reduce Ca increase evoked by the presence of mutant SOD1 in the axon terminals if the treatment was started presymptomatically but not at an early symptomatic stage. We also tested the Ca level in the cell bodies and axon terminals of the oculomotor neurons, which are resistant to the disease. Neither Ca increase, nor talampanel effect could be demonstrated at either time point. This is consistent with the observations that oculomotor neurons contain increased level of Ca buffer, which could reduce excess Ca load, and they also express glutamate receptor subunit type 2, which renders AMPA receptors impermeable to Ca.

Asymmetrical buffer allocation in unpaced merging assembly lines

Asymmetrical merging assembly lines are a research area which is rising in prominence due to increasing use in reverse logistics, remanufacturing, and developing economies. This paper studies the performance of reliable, unpaced merging assembly lines with asymmetric buffer storage sizes. Lines are simulated with varying line lengths, mean buffer storage capacities and uneven buffer allocation configurations. Contrary to typical manufacturing expectations, results indicate that production line imbalances do not always result in detrimental performance. Higher throughput and lower average buffer levels, as compared to a balanced merging line, are found where total available buffer capacity is allocated as evenly as possible, and with a higher buffer capacity concentration towards the end of the line. This paper contributes to total production line knowledge by providing performance improvement methods for unpaced merging assembly lines with asymmetrical buffer allocation, and inexpensive or no cost managerial options to increase productivity and resource utilization, and decrease waste, in asymmetrical merging assembly lines.

Exploring Associations Between Greenspace, Physical Activity, And Health Outcomes

PURPOSES: 1) To examine spatial effects of green space on health outcomes at various levels of geography; 2) To examine the potential mediating effect of physical activity on the relationship between green space and health outcomes. METHODS: Socio-demographic (e.g., sex, race, poverty, age) and health outcome variables (e.g., obesity, diabetes, heart disease, and mental health) were derived from the 2010-2015 Illinois Behavioral Risk Factor Surveillance System (BRFSS). Measures of green-space were created using tree canopy data from the 2011 National Land Cover Dataset (NLCD). Residential area was defined using measures of urban density by counting dwellings per 10 hectares. Green space was calculated for three levels of buffers, specifically 300m, 500m, 1km for each residential unit and the entire county where the residential unit was located. ArcGIS 10.3 (ESRI, CA), was used to geoprocessing all data. Residential green space was used as the primary independent variable while accounting for socio-demographic variables in regression analysis. RESULTS: Due to missing data, only 78 of 102 Illinois counties (76.47 %) were included in the analysis. The amount of green space, regardless of buffer level, has no association with health outcomes. Physical activity explained a significant proportion of variance only for diabetes all measures of green space: 300m, 500m, and 1000m for residential units (β= -.12, p<.03; R2=.30, p<0.001); county level (β= -.14, p<.02; R2=.31, p<.001). CONCLUSIONS: Although county level green space was negatively associated with physical activity, residential green space showed no association. This difference supports the importance of appropriately defining geographical units used for large-scale population-based. Further studies clarifying geographic units of analysis are required.

Revenue Management of Reusable Resources with Advanced Reservations

We consider a revenue management problem wherein the seller is endowed with a single type resource with a finite capacity and the resource can be repeatedly used to serve customers. There are multiple classes of customers arriving according to a multi‐class Poisson process. Each customer, upon arrival, submits a service request that specifies his service start time and end time. Our model allows customer advanced reservation times and services times in each class to be arbitrarily distributed and correlated. Upon arrival of each customer, the seller must instantaneously decide whether to accept this customer's service request. A customer whose request is denied leaves the system. A customer whose request is accepted is allocated with a specific item of the resource at his service start time. The resource unit occupied by a customer becomes available to other customers after serving this customer. The seller aims to design an admission control policy that maximizes her expected long‐run average revenue. We propose a policy called the ε‐ perturbation class selection policy ( ε‐CSP), based on the optimal solution in the fluid setting wherein customers are infinitesimal and customer arrival processes are deterministic, under the restriction that the seller can utilize at most (1 − ε) of her capacity for any ε ∈ (0, 1). We prove that the ε‐CSP is near‐optimal. More precisely, we develop an upper bound of the performance loss of the ε‐CSP relative to the seller's optimal revenue, and show that it converges to zero with a square‐root convergence rate in the asymptotic regime wherein the arrival rates and the capacity grow up proportionally and the capacity buffer level ε decays to zero.

Joint optimization of maintenance, buffers and machines in manufacturing lines

ABSTRACTThis article considers a series manufacturing line composed of several machines separated by intermediate buffers of finite capacity. The goal is to find the optimal number of preventive maintenance actions performed on each machine, the optimal selection of machines and the optimal buffer allocation plan that minimize the total system cost, while providing the desired system throughput level. The mean times between failures of all machines are assumed to increase when applying periodic preventive maintenance. To estimate the production line throughput, a decomposition method is used. The decision variables in the formulated optimal design problem are buffer levels, types of machines and times between preventive maintenance actions. Three heuristic approaches are developed to solve the formulated combinatorial optimization problem. The first heuristic consists of a genetic algorithm, the second is based on the nonlinear threshold accepting metaheuristic and the third is an ant colony system. The proposed heuristics are compared and their efficiency is shown through several numerical examples. It is found that the nonlinear threshold accepting algorithm outperforms the genetic algorithm and ant colony system, while the genetic algorithm provides better results than the ant colony system for longer manufacturing lines.

Optimization of Manufacturing Supply Chain with Stochastic Demand and Planned Delivery Time

In this paper, we study a manufacturing system composed by a single-product machine, a buffer and a constant demand. A stochastic fluid model is adopted to describe the system and to take into account delivery times and returned products from the customers (withdraw right). The objective of this paper is to determine the optimal buffer level taken into account machine failures, delivery times and withdrawal right. This optimal buffer allows minimizing the sum of inventory, transportation, lost sales and returned products costs. Infinitesimal perturbation analysis method is used for optimizing the proposed system. Using the stochastic fluid model, the trajectories of buffer level are studied and the infinitesimal perturbation analysis estimators are evaluated. These estimators are shown to be unbiased and then they are implanted in an optimization algorithm which determines the optimal buffer level in the presence of delivery time and withdrawal right.

Liquidity and Capital of Islamic Banks in Indonesia

This study is aimed to analyzed the factors that affect the liquidity and capital of Islamic banks in Indonesia. The method is used multiple linear regression. This result shows that the main problem of Islamic banks in Indonesia is how to increase equity in line with increasing third party fund. Another problem is that Islamic bank face difficulties to find debt for solving liquidity problem due to lack of instruments for liquidity derivative. Therefore Islamic banks rely on third party funds, which are high cost of funds due to time deposit fund, rather than using current deposit and saving deposit fund. Another result, negative coefficient of Gross Domestic Product (GDP) to Quick Ratio (QR) indicate that if macroeconomics of Indonesia is stable and good environment, Islamic banks will expansive the market, meanwhile Islamic banks have now low level of liquidity buffer. This means Islamic banks face high level of risk, if core depositors withdraw money rushly it became defaultDOI: 10.15408/sjie.v6i1.4405

Working Memory in Aphasia: Considering Discourse Processing and Treatment Implications.

Evidence suggests that persons with aphasia (PWAs) present with working memory impairments that affect a variety of language tasks. Most of these studies have focused on the phonological loop component of working memory and little attention has been paid to the episodic buffer component. The episodic buffer, as a limited capacity, multimodal system that binds and integrates information from the phonological loop, visuospatial sketchpad, and long-term memory would likely be involved in discourse processing. The purposes of this article were to (1) review discourse level deficits associated with aphasia, (2) describe how a deficit at the level of the episodic buffer could cause such deficits, (3) to review discourse treatment approaches for PWAs, and (4) present preliminary results from a novel discourse treatment study for PWAs.

무선망 특성을 고려한 효율적 비디오 스트리밍 재생률 선택 기술

Explosive deployment of smart mobile devices such as smart phones, and tablets along with expansion of wireless internet bandwidth have enabled the deployment of mobile video streaming such that video traffic becomes the most important service in wireless networks. Recently, for more efficient video streaming services, the ISO MPEG group standardized a protocol called DASH (Dynamic Adaptive Streaming over HTTP) and the standard has been quickly adopted by many service providers such as YouTube and Netflix. Despite of the convenience of mobile streaming services, users also suffer from low QoE(Quality of Experience) due to dynamic channel fluctuations and unnecessary downloading due to high churning rates. This paper proposes a noble efficient video rate selection algorithm considering user buffer level, channel condition and churning rate. Computer simulation based performance study showed that the proposed algorithm improved the QoE significantly compared to a method that determines the video rate based on current channel conditions. Especially, the proposed method reduced the rebuffering rate, one of the most important performance factors of the QoE, to a nonnegligible level.

Cycle time-oriented mid-term production planning for semiconductor wafer fabrication

Wafers are produced in an environment with uncertain demand and failure-prone machines. Production planners have to react to changes of both machine availability and target output, and revise plans appropriately. The scientific community mostly proposes WIP-oriented mid-term production planning to solve this problem. In such approaches, production is planned by defining targets for throughput rates and buffer levels of selected operations. In industrial practice, however, cycle time-oriented planning is often preferred over WIP-oriented planning. We therefore propose a new linear programming formulation, which facilitates cycle time-oriented mid-term production planning in wafer fabrication. This approach plans production by defining release quantities and target cycle times up to selected operations. It allows a seamless integration with the subordinate scheduling level. Here, least slack first scheduling translates target cycle times into lot priorities. We evaluate our new methodology in a comprehensive simulation study. The results suggest that cycle time-oriented mid-term production planning can both increase service level and reduce cycle time compared to WIP-oriented planning. Further, it requires less modelling effort and generates plans, which are easier to comprehend by human planners.

Simulating Fire-Sales in a Banking and Shadow Banking System

We develop an agent based model of traditional banks and asset managers. Our aim is to investigate the channels of contagion of shocks to asset prices within and between the two financial sectors, including the effects of fire sales and their impact on financial institutions’ balance sheets. We take a structural approach to the price formation mechanism as in Bluhm, Faia and Kranen (2014) and introduce a clearing mechanism with an endogenous formation of asset prices. Both types of institutions hold liquid and illiquid assets and are funded via equity and deposits. Traditional banks are interconnected in the money market via mutual interbank claims, where the rate of return is endogenously determined through a tatonnement process. We show how in such a set-up an initial exogenous liquidity shock may lead to a fire-sale spiral. Banks, which are subject to capital and liquidity requirements, may be forced to sell an illiquid security, which impacts its, endogenously determined, market price. As the price of the security decreases, both agents update their equity and adjust their balance sheets by making decisions on whether to sell or buy the security. This endogenous process may trigger a cascade of sales leading to a fire-sale. We find that, first, mixed portfolios banks act as plague-spreader in a context of financial distress. Second, higher bank capital requirements may aggravate contagion since they may incentivise banks to hold similar assets, and choose mixed portfolios business model which is also characterized by lower levels of voluntary capital buffer. Third, asset managers absorb small liquidity shocks but they exacerbate contagion when liquid buffers are fully utilised.

A Probabilistic Adaptation Method for HTTP Low-Delay Live Streaming over Mobile Networks

The study focuses on the adaptation problem for HTTP low-delay live streaming over mobile networks. In this context, the client's small buffer could be easily underflown due to throughput variations. To maintain seamless streaming, we present a probabilistic approach to adaptively decide the bitrate for each video segment by taking into account the instant buffer level. The experimental results show that the proposed method can significantly reduce buffer underflows while providing high video bitrates.

The Impact of Bank Income Diversification on Capital Buffer Periodicity

Based on the panel data of 16 listed banks in China from 2004 to 2014, this paper makes empirical analysis to examine the relationship between bank’s capital buffer and macroeconomic fluctuations or income diversification. The results show that the banks’ income diversification has negatively correlation with macroeconomic fluctuations. It means the banks’ capital buffer behaves in a counter-cyclical way, and different bank ownership structure or capital level also has asymmetric influence in expansion and slack time. What’s more, the non-interest income of bank has a significant negative impact on capital buffer and its periodicity. The diversification of bank income structure not only reduces the bank’s capital buffer level, but also weakens the counter-cyclical characteristics of capital buffer. At the same time, the diversification of the income structure of the bank with high capital adequacy ratio has no obvious effect on the counter-cyclical characteristics of the capital buffer. Based on the above conclusions, this paper believes that the regulatory authorities in the implementation of the counter-cyclical capital regulation should fully consider the impact of bank income structure and bank capital levels.

Bit Rate Control for Video Transmission Over Wireless Networks

This paper developed a model of bit- rate control for video streaming over constant bit-rate communication channel, where the MPEG-2, standard Variable Bit-Rate (VBR), is adapted to be used as a Constant Bit Rate (CBR). The targeted image quality is based on the buffer level controlling on the output rate of the video encoder. A CBR transport over networks, result is better performing than that of VBR. It provided flexibility to monitor network and to analyse, where the VBR video streaming over CBR channel can be chosen to remove the problem of congestion. This paper makes the study about the basic problem of adapted VBR-compress the video for transport over a CBR channel. The improved systems are carried using Matlab (Ver 6.5) under Windows XP operating system.

Improving QoE and Fairness in HTTP Adaptive Streaming Over LTE Network

HTTP adaptive streaming (HAS) has emerged as the main technology for video streaming applications. Multiple HAS video clients sharing the same wireless channel may experience different video qualities as well as different play-out buffer levels, as a result of both different video content complexities and different channel conditions. This causes unfairness in the end-user quality of experience. In this paper, we propose a quality-fair adaptive streaming solution with fair buffer (QFAS-FB) to deliver fair video quality and to achieve asymptotically fair play-out buffer levels among HAS clients competing for the same wireless resources in a long-term evolution (LTE) cell. In the QFAS-FB framework, the share of radio resources is optimized according to video content characteristics, play-out buffer levels, and channel conditions. The proposed solution is compared with the other state-of-the-art strategies, and the numerical results show that it significantly improves the quality fairness among heterogeneous HAS users, reduces the video quality variations, and improves the fairness among the user’s play-out buffers.

Energy management of a plug-in fuel cell/battery hybrid vehicle with on-board fuel processing

This paper describes the energy management controller design of a mid-sized vehicle driven by a fuel cell/battery plug-in hybrid powertrain, where an experimentally validated hight temperature polymer electrolyte membrane fuel cell model is used. The power management strategy is derived by the application of the Pontryagin’s Minimum Principle, where the control parameter is adapted by using feedback information on the state of charge and total trip length forecast as a function of a moving average of past information about the driving cycle speed. The strategy we propose aims at achieving a real time sub-optimal solution of the control problem which is cast into the minimization of the consumed fuel. The vehicle is also equipped by an auto-thermal reformer and, in order to minimize the hydrogen buffer size, the control algorithm is subject to constraints on the maximum hydrogen buffer level. A comparative analysis of the proposed strategy against the optimal one is conducted and results are reported. The obtained fuel consumptions are also compared to those obtained by the same vehicle, powered by an internal combustion engine and by a plug-in hybrid electric powertrain.