Buffer Level Research Articles

Maternal exposure to ambient particulate matter and green spaces and fetal renal function

Exposure to air pollution has been associated with different harmful effects and exposure to greenspace has been related to improved human health. However, the available evidence on the impact of these exposures on renal function is still scarce. The aim of this study was to determine the relationship between exposure to ambient levels of PM1, PM2.5, PM10 and indicators of exposure to traffic as well as greenspace during pregnancy and fetal renal function based on the umbilical cord blood. This study was based on 150 pregnant women residing in Sabzevar, Iran (2018). Multiple linear regression models were developed to estimate the association of glomerular filtration rate (GFR), creatinine (Cr) and blood urea nitrogen (BUN) with exposure to air pollution, traffic, and greenspace (one at a time) controlled for relevant covariates. There was an inverse significant association between exposure to PM1, PM2.5, PM10 and total street length in a 100 m buffer around the home and eGFR. Increase in distance to major road and residential surrounding greenness (100 m buffer) was associated with increase in eGFR. We observed a significant direct association between exposure to PMs as well as street length in 100 m buffer and serum level of Cr. There was also an inverse association between distance to major road and NDVI in 100 m buffer and Cr. The associations for blood urea nitrogen (BUN) were not statistically significant. Our results suggest that exposure to air pollution during pregnancy could have negative impact and exposure to greenspace could have positive impact on renal function of fetal.

Buffer allocation, equipment selection and line balancing optimisation in unreliable production lines

This paper presents an integrated optimisation model to simultaneously solve buffer allocation, equipment selection and line balancing problems in unreliable production line systems. The considered unreliable serial production line consists of m workstations and m − 1 intermediate buffers. The objective is to maximise the system throughput level. A decomposition method is used to estimate the production line throughput. The decision variables in the formulated optimal design problem are buffer levels, types of equipment and the sets of tasks assigned to the workstations. An efficient algorithm, based on the nonlinear threshold accepting algorithm (NLTA) is proposed to solve this problem. The efficiency of the proposed approach is compared to existing algorithms and first tested on a simple assembly line balancing type-2 problem (SALB-2). Here the objective is to minimise the cycle time with a fixed number of workstations. In the second numerical experiment, the integrated model is solved using the NLTA, and its performance is compared to that of the great deluge algorithm (GDA) through several numerical examples. [Received: 9 June 2018; Revised: 15 September 2018; Revised: 18 April 2019; Accepted: 2 August 2019]

Smart control of the assembly process with a fuzzy control system in the context of Industry 4.0

Assembly line balancing is important for the efficiency of the assembly process, however, a wide range of disruptions can break the current workload balance. Some researchers explored the task assignment plan for the assembly line balancing problem with the assumption that the assembly process is smooth with no disruption. Other researchers considered the impacts of disruptions, but they only explored the task re-assignment solutions for the assembly line re-balancing problem with the assumption that the re-balancing decision has been made already. There is limited literature exploring on-line adjustment solutions (layout adjustment and production rate adjustment) for an assembly line in a dynamic environment. This is because real-time monitoring of an assembly process was impossible in the past, and it is difficult to incorporate uncertainty factors into the balancing process because of the randomness and non-linearity of these factors. However, Industry 4.0 breaks the information barriers between different parts of an assembly line, since smart, connected products, which are enabled by advanced information and communication technology, can intelligently interact and communicate with each other and collect, process and produce information. Smart control of an assembly line becomes possible with the large amounts of real-time production data in the era of Industry 4.0, but there is little literature considering this new context. In this study, a fuzzy control system is developed to analyze the real-time information of an assembly line, with two types of fuzzy controllers in the fuzzy system. Type 1 fuzzy controller is used to determine whether the assembly line should be re-balanced to satisfy the demand, and type 2 fuzzy controller is used to adjust the production rate of each workstation in time to eliminate blockage and starvation, and increase the utilization of machines. Compared with three assembly lines without the proposed fuzzy control system, the assembly line with the fuzzy control system performs better, in terms of blockage ratio, starvation ratio and buffer level. Additionally, with the improvement of information transparency, the performance of an assembly line will be better. The research findings shed light on the smart control of the assembly process, and provide insights into the impacts of Industry 4.0 on assembly line balancing.

Social-Aware D2D Video Delivery Method Based on Mobility Similarity Measurement in 5G Ultra-Dense Network

The huge amounts of network traffic generated by the ultra-high-definition video playback of super-large-scale video users results in tremendous pressure for front-haul and back-haul in the 5G network, which brings severely negative influence for the large-scale deployment and scalability of video systems and video delivery performance (e.g. transmission delay and packet loss) related to user quality of experience. The direct D2D communications between mobile devices with adjacent position in geographical area can offloading huge video traffic into the underlying networks, which reduces load of cellular base station in the edge networks and relieves traffic pressure in the core networks. In this paper, we propose a novel Social-Aware D2D Video Delivery Method based on Rapid Sample-Efficient Measurement of Mobility Similarity in 5G Ultra-Dense Network (DMSEM). By investigation for one-hop D2D pair relationship, DMSEM builds a social state transition model of user movement, which makes use of encounter duration and shared video length between encountered users to define the state transition condition. A cluster algorithm of encounter events is proposed, which achieves initial clusters of encounter events by calculating similarity between encounter events from the two aspects of both variation rate of geographical distance between mobile users and encounter duration time. DMSEM makes use of the Fuzzy C-Means to refine the initial clusters and extracts encounter patterns of mobile users. DMSEM designs a sample-efficiency rapid recognition algorithm of encounter pattern, which can use small number of encounter distance samples to achieve fast heuristic recognition of encounter pattern. Extensive tests show how DMSEM achieves better results in comparison with other state-of-the-art solutions in terms of packet loss rate, average freeze time, cache utilization, average bitrate, buffer level and control overhead.

Effects of temperature on physiological performance and behavioral thermoregulation in an invasive fish, the round goby.

ABSTRACTInvasive species exert negative impacts on biodiversity and ecosystems on a global scale, which may be enhanced in the future by climate change. Knowledge of how invasive species respond physiologically and behaviorally to novel and changing environments can improve our understanding of which traits enable the ecological success of these species, and potentially facilitate mitigation efforts. We examined the effects of acclimation to temperatures ranging from 5 to 28°C on aerobic metabolic rates, upper temperature tolerance (critical thermal maximum, CTmax), as well as temperature preference (Tpref) and avoidance (Tavoid) of the round goby (Neogobius melanostomus), one of the most impactful invasive species in the world. We show that round goby maintained a high aerobic scope from 15 to 28°C; that is, the capacity to increase its aerobic metabolic rate above that of its maintenance metabolism remained high across a broad thermal range. Although CTmax increased relatively little with acclimation temperature compared with other species, Tpref and Tavoid were not affected by acclimation temperature at all, meaning that round goby maintained a large thermal safety margin (CTmax−Tavoid) across acclimation temperatures, indicating a high level of thermal resilience in this species. The unperturbed physiological performance and high thermal resilience were probably facilitated by high levels of phenotypic buffering, which can make species readily adaptable and ecologically competitive in novel and changing environments. We suggest that these physiological and behavioral traits could be common for invasive species, which would only increase their success under continued climate change.

Reliability Evaluation for Manufacturing System Based on Dynamic Adaptive Fuzzy Reasoning Petri Net

Due to failure, partial failure, or maintenance, the capacity of each machine is multi-state. Therefore, the limited relationship between the capacity of each machine and the input raw materials has to be considered. Additionally, in order to utilize the machine more effectively, the capacity of the buffers cannot be ignored, too. In this paper, a dynamic adaptive fuzzy reasoning Petri net is proposed to evaluate reliability of a manufacturing system with multiple production lines. Firstly, the model of manufacturing system is conducted, and from the perspective of demand, the minimum capacity vector and loading vector of each machine are determined. Secondly, knowledge representation and rules are formulated to establish weighted fuzzy petri nets. And the weighted fuzzy Petri net is adaptive based on the real-time level of buffers, the minimum capacity vector and loading vector. Moreover, the efficiency of product production can be improved while ensuring system reliability by adjusting the buffer level. Finally, a numerical experiment is used to demonstrate the application of our method.

A Hierarchical Buffer Management Approach to Rate Adaptation for 360-Degree Video Streaming

For the 360-degree virtual reality (VR) videos, to achieve the same user-perceived playout quality with traditional video, the overall video bitrate has to be much higher, which significantly increases the bandwidth requirement. To overcome this issue, most of rate adaptation schemes are proposed based on the users' Field of View (FoV), since users only view part of the entire videos when watching 360-degree videos. However, the FoV prediction is only valid in short terms which incurs low robustness against network dynamics and results in frozen screen events. Since the playback buffer can effectively avoid re-buffering by storing videos in advance, we propose a two-layered hierarchical buffer-based rate adaptation scheme for 360-degree VR videos in this paper. The tiles will be updated to enhance the video quality in the short buffer layer based on FoV prediction, meanwhile the long buffer layer takes charge of downloading new chunks to guarantee the buffer occupancy. To better improve the quality of experience (QoE), we jointly consider the users' FoV, channel conditions and buffer status. Our method achieves a good trade-off between video quality and buffer occupancy. Besides, the maximum buffer level selection is optimized to further improve the performance. The simulation results show that our proposed scheme and algorithms outperform other methods by about 5%-30% of QoE improvement.

Adaptación de las condiciones de tamponamiento de un sistema de fermentación in vitro para el estudio de la acidosis ruminal

Ruminal acidosis is an important disease of cattle production. The development of in vitro techniques suitable for its study would allow to reduce costs and accelerate the times to achieve results useful to contribute to the increase of production, minimally affecting animal welfare. In the present study, a “gas in vitro” method was modified using different buffer solutions (artificial saliva) to assess their buffering effect in simulated ruminal acidosis situations. Three successive tests were carried out. An artificial saliva formulated for studies that required a high buffering level (SA01) was first tested, verifying that it was not appropriate for the simulation of acidosis. Five variations in the composition of saliva SA01 were then studied and finally two saliva were tested with a different composition and elaboration methods. Differences in the evolution of pH in the fermentation systems were studied through their comparison in four times of fermentation (0, 4, 12 and 24h) with control treatments with buffered systems without triggering the simulated acidosis by Student’s t (α = 0.05) and through the comparison of the parameters obtained by means of a non-linear regression of the values obtained from each treatment, adjusting it to a descending logarithmic model. Although the three artificial salivas studied in the last experiment could meet the sought objective, the artificial saliva SA03, with a lower amount of bicarbonate and higher proportion of phosphates, was the one that presented the best behavior for the analysis of acidosis situations.

Coups d'état and the foreign exchange market

AbstractI empirically examine the effect of coups d'état on the foreign exchange market using a monthly panel dataset covering 150 countries over the period 1980–2015. Specifically, I investigate whether foreign exchange market's participants sanction a country following a coup d'état event by allowing depreciations of its national currency against a weighted basket of currencies of its trading partners. I combine different identification strategies and find that the occurrence of a coup d'état induces a depreciation of the nominal effective exchange rate in the coup d'état country and generates negative spillover effects on neighbouring countries. Once a coup occurs, a country level of financial buffers and the flexibility of its exchange rate regime allow reducing the magnitude of the depreciation. In addition, I provide evidence that coups also increase the likelihood of experiencing a currency crisis by about 2 percentage points in coup d'état countries compared to non‐coup d'état countries.

Simulating fire sales in a system of banks and asset managers

We develop an agent-based model of traditional banks and asset managers to investigate the contagion risk related to fire sales and balance sheet interactions. We take a structural approach to the price formation in fire sales as in Bluhm et al. (2014) and introduce a market clearing mechanism with endogenous formation of asset prices. We find that, first, banks which are active in both the interbank and securities markets act as plague-spreaders during financial distress. Second, higher bank capital requirements may aggravate contagion by creating incentives for banks to increase exposures in the interbank market, which also leads to lower levels of a voluntary capital buffer above the minimum capital requirement. Third, asset managers absorb small liquidity shocks, but they exacerbate contagion when their voluntary liquid buffers are fully utilised. Fourth, a system with larger and more interconnected agents is more prone to contagion risk stemming from funding shocks.

Switching- and hedging- point policy for preventive maintenance with degrading machines: application to a two-machine line

Maintenance and production are frequently managed as separate activities although they do interact. Disruptive events such as machine failures may find the company unready to repair the machine immediately leading to time waste. Preventive Maintenance may be carried out and maintenance time reduced to the effective task duration, in order to prevent time waste. Companies and researchers have been focusing on policies able to mitigate the impact of Preventive Maintenance on system availability, by exploiting the knowledge about degradation profiles in machines and the joint information from the machine state and the buffer level. In this work, the mathematical proof of the optimal threshold-based control policy for Preventive Maintenance with inventory cost, maintenance cost, backlog cost is provided. The control policy is defined in terms of buffer thresholds and dependency of the thresholds on the degradation condition. The optimal control policy is proved to include a combination of switching points and hedging points, where the first ones activate the Preventive Maintenance for a given condition and the latter ones control the production rate in order to minimize the surplus. An extensive experimental campaign analyzes the impact of system parameters such as the Maintenance duration on the cost function. The results show that there exists cases in which the optimal policy is dominated by the effect of the hedging points or the switching points, alternatively. Therefore, the proposed method is used to provide suggestions to the management for operative decisions, in order to choose the policy fitting best the system.

Development of a Novel Enzymatic Pretreatment for Improving the Digestibility of Protein in Feather Meal

This study describes the process of developing an enzymatic pretreatment to improvethe nutritional value of feather meal (FeM). In a first experiment, a full factorial design was used toexamine the effects of various incubation conditions on the solubilization of nitrogen in FeM. Weincubated FeM for 3 h with various levels of a commercial alkaline serine protease (Savinase®16L), sodium sulphite (Na2SO3), and digestion buffer. A Savinase® 16L level of 3% (%FeM v/w),Na2SO3 level of 3% (%FeM w/w), and digestion buffer level of 500% (%FeM w/w) were identifiedas the optimal conditions. Under these optimal conditions, 45% of the nitrogen in FeM wassolubilized. In a second experiment, we evaluated the effect of more economically sustainableincubation conditions on the in vitro digestibility of protein (pepsin-HCl digestibility andmultistep protein evaluation) in FeM. Two FeMs were incubated with 0.5% Savinase® 16L (%FeMv/w), 2% Na2SO3 (%FeM w/w), and 200% buffer (%FeM w/w) for 24 h. The pretreatment improvedpepsin-HCl digestibility by 7%–16% and the total tract degradable protein content by 14%–50%.Accordingly, this novel pretreatment could be applied in the animal feed industry to improve thenutritional value of FeM.

Risk assessments in orthodontic patients developing white spot lesions.

To determine whether caries risk factors, including cariogenic bacterial levels and salivary function, can be used to identify orthodontic patients who develop white spot lesions (WSL). This prospective case-control study comprised 50 patients 11-17years of age, including 25 controls and 25 cases who developed new WSL during treatment. WSL, oral hygiene and fluorosis were evaluated from intraoral photographs. The biofilm was assessed with bacterial cultures and adenosine triphosphate (ATP) bioluminescence. Salivary analyses were performed to determine the pH of saliva and flow rates. A survey was used to assess snacking frequency, oral hygiene and fluoride utilization. There were no between-group pretreatment differences in WSL. Cases reported eating sugary foods significantly more often than the controls. There was a significant decline in oral hygiene during treatment, with no significant between-group difference. There also were no statistically significant between-group differences in the amount of saliva, buffer, ATP bioluminescence and bacterial levels. Both groups showed lower than normal buffer capacity and high bacterial levels. Cases had greater sugar intake between meals than controls. ATP bioluminescence, Streptococcus mutans levels with Saliva Check Mutans, and salivary factors do not identify patients who develop WSL.

The Impact of the Regulation of LTV and DTI of Korean Policy Mortgage Loans on the Loans for Household in Commercial Banks

ABSTRACTThis study examined the effects of reinforcing the regulation of policy mortgage loans on household loans provided by Korean commercial banks when the interest rate went up alongside the climbing U.S. federal rate. The main results of this study are as follows: First, regarding the soundness of the policy of tightly regulating loans, lowering the loan-to-value (LTV) and the debt-to-income (DTI) ratios may increase the supply of loans for households. The current study infers that the reduction of policy loans results in expanding the housing loan supply in commercial banks. Second, the tight regulation of mortgage policy led to a rapid increase in household loans. This evidence is related to the theoretical underpinning that adjustment of loan portfolios in commercial banks is made flexible according to external shocks. Third, an increase in the capital buffer in commercial banks has a negative effect on the expanding supply of housing loans. Therefore, activity above the capital buffer level is associated with the growth of risky loans. In conclusion, the tight regulation of policy mortgage loans may increase the supply of mortgage loans within the household credit segment of commercial banks.

Dynamic alternate buffer switching and congestion control in wireless multimedia sensor networks

Normally sensor nodes are located at unattended environment which has low battery power. The wireless hypermedia sensor based networks have huge capacity and continuous flow of data from source to sink. Congestion arises at the time of incoming data is greater than available resources. The congestion causes packet loss, buffer over flow, energy wastage and increases end to end delay. The proposed method Dynamic Alternate Buffer switching and Congestion Control is used to manage congestion in an efficient manner. In which congestion is detected based on remaining buffer, remaining energy and trust level of the sensor nodes. This approach is based on cost evaluation method which decides primary and spare buffers at run time. This method is used to enable dynamic buffer switching and optimize the effect of congestion. The performance of BETCC compared with various existing protocol like TCEER and TFCC in terms of energy consumption and data loss ratio.

An agile scheduling and control approach in ETO construction supply chains

A special characteristic of Engineer-to-Order (ETO) construction supplier companies is that they are composed of an off-site and on-site production part. Often, their synchronization is difficult by using traditional scheduling and monitoring methodologies resulting in excessive lead times, buffer levels and, as a result, additional costs. Real-time data, made available by Industry 4.0 technologies, represent a high potential to sense and react to plan deviations as soon as they appear. The paper presents a decentralized and agile approach for scheduling and control in ETO construction supply chains. The approach was modelled and validated based on a case study of an ETO façade supplier company and a discrete event simulation. It emerged that the agile approach has its main benefits in the reduction of buffer sizes and construction lead-times. The original aspect of the article is the investigation of effects of agile scheduling and control in ETO construction supply chains.

Sensitivity of occupant comfort models to humidity and their effect on cooling energy use

Residential building energy consumption in the United States has decreased steadily during the last several decades largely because of advances in building codes as well as voluntary efficiency and labeling programs, which have resulted in the reduction in building sensible loads. Building latent loads have not decreased by the same amount, and field and analytical research studies have concluded that high-efficiency, low-load homes often have elevated indoor humidity levels, possibly leading to occupant discomfort. There are discrepancies in the literature on occupant comfort as it relates to indoor humidity and recommended upper humidity limits. The choice of humidity limit could potentially change results and conclusions on the energy impacts of a new air conditioner or dehumidifier technology, changing ventilation rates, or an improved building envelope. In this study, we use building simulations to explore the impact of humidity control on cooling energy use in efficient residential buildings for different humidity limits. We look at limits based on humidity ratio (or dew point temperature), wet-bulb temperature, relative humidity, and constant slope lines based on the popular comfort models of both Fanger and Gagge. We quantify the additional energy use required to control humidity below these limits. We look at the sensitivity of the results to different temperature and humidity set points, occupant internal gains, moisture buffering levels, evaporator airflow rates, and dehumidifier energy factors. High-efficiency home predicted energy savings are more sensitive to the assumed humidity limit and cooling and dehumidification set points than the other parameters investigated in this paper.

MiSAL - A minimal quality representation switch logic for adaptive streaming

Quality of Experience is affected by many parameters. For this reason, client-side adaptation logic algorithms often adopt the strategy of optimizing a subset of parameters in the hope of improving the overall QoE. However, as shown here, this approach ends up degrading parameters that are crucial to good Quality of Experience. To resolve this conundrum, we present a new approach for improved Quality of Experience dubbed: Minimal Switch AL (MiSAL). This algorithm substantially reduces the number of quality level switches by monitoring the client buffer level and carefully estimating the channel bandwidth and the Round Trip Time. A comparison of MiSAL against leading ALs demonstrates that this approach successfully in optimizes several important parameters that affect Quality of Experience without negatively affecting other parameters. It is shown that MiSAL can provide a close to optimal QoE under many different network conditions.

Flexible preventative maintenance for serial production lines with multi-stage degrading machines and finite buffers

In production systems, machines are typically subject to degradation, which is a gradual and accumulating process that can influence the performance of the production systems. In this work, we focus on the flexible preventative maintenance problem on serial production lines with multi-stage degrading machines and finite buffers. Condition-based maintenance decisions are first investigated for a two-machine-one-buffer system, considering machine degradation stages and the buffer level. The optimal maintenance policy is obtained using Markov decision models. For longer lines, approximation methods are developed based on the results from the two machine case. Specifically, an iterative state and machine aggregation approach is developed to find the optimal preventative maintenance policy for each machine in large systems. Numerical experiments show that the proposed method outperforms the state-of-the-art.

Does parental warmth buffer the relationship between parent-to-child physical and verbal aggression and adolescent behavioural and emotional adjustment?

ABSTRACT The aim of this study was to evaluate whether childhood levels of parental warmth buffer the relationship between parent-to-child physical and verbal aggression and behavioural and emotional adjustment (violent offending, substance use, depression and anxiety) among adolescent boys and girls. Data were drawn from a large self-report school survey conducted among 9th graders in Lower Saxony, Germany (n = 7423). Controlling for socio-demographic factors and risk-seeking, results showed that parent-to-child physical and verbal aggression were related to increased externalizing and internalizing behaviour, while parental warmth was related to decreased anxiety and depression. Perceived parental warmth during childhood buffered effects of parent-to-child verbal aggression on later violent offending. More specifically, the strongest relationship between parent-to-child verbal aggression and externalizing behaviour was found in individuals with low parental warmth. Child and parent gender did not qualify the moderating effect of warmth. Results underscore the need for programmes and policies that promote stable family environments particularly marked by the absence of parent-to-child physical and verbal aggression.