Mixing Costs Research Articles

An improved imperialist competitive algorithm based photolithography machines scheduling

: Photolithography machine is one of the most expensive equipment in semiconductor manufacturing system, and as such is often the bottleneck for processing wafers. This paper focuses on photolithography machines scheduling with the objective of total completion time minimisation. In contrast to classic parallel machines scheduling, it is characterised by dynamical arrival wafers, re-entrant process flows, dedicated machine constraints and auxiliary resources constraints. We propose an improved imperialist competitive algorithm (ICA) within the framework of a rolling horizon strategy for the problem. We develop a variable time interval-based rolling horizon strategy to decide the scheduling point. We address the global optimisation in every local scheduling by proposing a mixed cost function. Moreover, an adaptive assimilation operator and a sociopolitical competition operator are used to prevent premature convergence of ICA to local optima. A chaotic sequence-based local search method is presented to accelerate the rate of convergence. Computational experiments are carried out comparing the proposed algorithm with ILOG CPLEX, dispatching rules and meta-heuristic algorithms in the literature. It is observed that the algorithm proposed shows an excellent behaviour on cycle time minimisation while with a good on time delivery rate and machine utilisation rate.

The relationship between general executive functions and bilingual switching and monitoring in language production

We examined the role of general inhibitory control and general set shifting processes in bilingual language production in 51 native Finnish speakers with English as L2, mainly learnt after the age of 7. We tested the hypothesis that inhibitory control, measured with the Simon and Flanker tasks, is central when switching into L1 (Green, 1998) and, more generally, that general set shifting processes, measured with the Number-Letter task, underlie language switching and mixing (Meuter & Allport, 1999). The results were inconsistent. The basic language switch cost effects were in line with the inhibitory control model, but the interactions with the executive tasks did not support the model and were partly contrary to it. The general set shifting hypothesis received some support. Alternative explanations of the sources of the switching and mixing cost asymmetries in bilingual language production are discussed.

Impact of misspecified residual correlation structure on the parameter estimates in a shared spatial frailty model

ABSTRACTIn practice, survival data are often collected over geographical regions. Shared spatial frailty models have been used to model spatial variation in survival times, which are often implemented using the Bayesian Markov chain Monte Carlo method. However, this method comes at the price of slow mixing rates and heavy computational cost, which may render it impractical for data-intensive application. Alternatively, a frailty model assuming an independent and identically distributed (iid) random effect can be easily and efficiently implemented. Therefore, we used simulations to assess the bias and efficiency loss in the estimated parameters, if residual spatial correlation is present but using an iid random effect. Our simulations indicate that a shared frailty model with an iid random effect can estimate the regression coefficients reasonably well, even with residual spatial correlation present, when the percentage of censoring is not too high and the number of clusters and cluster size are not too low. Therefore, if the primary goal is to assess the covariate effects, one may choose the frailty model with an iid random effect; whereas if the goal is to predict the hazard, additional care needs to be given due to the efficiency loss in the parameter(s) for the baseline hazard.

Relationship between language switching experience and executive functions in bilinguals: an Internet-based study

ABSTRACTWe examined the relationship between self-reported everyday language switching experience and the performance of early bilinguals in tasks measuring different executive functions. Our participants were Finnish–Swedish early bilinguals, aged 16–41 years (N = 66, Experiment 1) and 18–69 years (N = 111, Experiment 2). An earlier study using a sample from a similar population discovered a negative relationship between self-reported language switching and a mixing cost in error rates in a number–letter task. This finding was not replicated. Instead, we found that a higher rate of reported contextual language switching predicted larger switching cost reaction times in the number–letter task, and that a higher rate of reported unintended language switches predicted larger error rates in a spatial n-back task. We conclude that these results likely reflect individual differences in executive skills, and do not provide evidence for the hypothesis that language switching trains executive functions.

ANALYSIS OF MARKETING MIX AND SALES PERFORMANCE OF “INDUSTRI HILIR TEH WALINI” PRODUCT

This research as a case study in “Industri Hilir Teh Walini” aimed to: (1) describe the marketing mix strategy, (2) examine the influence of marketing mix strategy on sales, (3) know the sales performance of products, (4) forecast the future demand of primary products, and (5) explore the strengths, weaknesses, opportunities, and threats (SWOT).Descriptive explanation, multiple linear regression analysis, one way analysis of variance, moving average forecasting, and SWOT analysis were conducted. This research showed that in the product mix as a component of marketing mix, this business unit offers tea products in various packaging and flavoring. The price determination conducted based on cost, market competition, and standards in certain lines. The promotion mix used are Above and Below The Line communication strategy. The place mix conducted by distributing products through selective distribution channel and direct channel. Promotion cost and flavor variants variables of the marketing mix were proven to have positive significant influence on the sales. Based on the one way analysis of variance, grouped tea product sales of tea bag, loose and instant tea, and ready to drink tea were significantly different. Forecast of black tea bag, lemon flavored black tea bag, and green tea bag sales volume in 2014 which give the best sales performance tend to be fluctuated. The SWOT analysis showed that this business unit’s position is in quadrant 1 which supports the SO (Strengths-Opportunities) strategy.

Economic feasibility of microalgal bacterial floc production for wastewater treatment and biomass valorization: A detailed up-to-date analysis of up-scaled pilot results

The economic potential of outdoor microalgal bacterial floc (MaB-floc) raceway ponds as wastewater treatment technology and bioresource of biomass for fertilizer, shrimp feed, phycobiliproteins and biogas in Northwest Europe is assessed. This assessment is based on cost data provided by industry experts, on experimental data obtained from pilot-scale outdoor MaB-floc ponds treating aquaculture and food-industry effluents, and from different biomass valorization tests. MaB-floc ponds exhibit a cost-performance of EUR 0.25–0.50m−3 wastewater which is similar to conventional wastewater treatment technologies. The production cost of MaB-flocs in aquaculture and food industry effluent is EUR 5.29 and 8.07kg−1TSS, respectively. Capital costs and pond mixing costs are the major expenses. Commercializing MaB-flocs as aquaculture feed generates substantial revenues, but the largest profit potential lies in production of high-purity phycobiliproteins from MaB-flocs. These results highlight the large economic potential of MaB-floc technology, and justify its further development.

Age-related decline in task switching is linked to both global and tract-specific changes in white matter microstructure.

Task-switching performance relies on a broadly distributed frontoparietal network and declines in older adults. In this study, they investigated whether this age-related decline in task switching performance was mediated by variability in global or regional white matter microstructural health. Seventy cognitively intact adults (43-87 years) completed a cued-trials task switching paradigm. Microstructural white matter measures were derived using diffusion tensor imaging (DTI) analyses on the diffusion-weighted imaging (DWI) sequence. Task switching performance decreased with increasing age and radial diffusivity (RaD), a measure of white matter microstructure that is sensitive to myelin structure. RaD mediated the relationship between age and task switching performance. However, the relationship between RaD and task switching performance remained significant when controlling for age and was stronger in the presence of cardiovascular risk factors. Variability in error and RT mixing cost were associated with RaD in global white matter and in frontoparietal white matter tracts, respectively. These findings suggest that age-related increase in mixing cost may result from both global and tract-specific disruption of cerebral white matter linked to the increased incidence of cardiovascular risks in older adults. Hum Brain Mapp 38:1588-1603, 2017. © 2016 Wiley Periodicals, Inc.

Alterations in brain white matter contributing to age-related slowing of task switching performance: The role of radial diffusivity and magnetization transfer ratio.

Successfully switching between tasks is critical in many daily activities. Age-related slowing of this switching behavior has been documented extensively, but the underlying neural mechanisms remain unclear. Here, we investigated the contribution of brain white matter changes associated with myelin alterations to age-related slowing of switching performance. Diffusion tensor imaging derived radial diffusivity (RD) and magnetization transfer imaging derived magnetization transfer ratio (MTR) were selected as myelin sensitive measures. These metrics were studied in relation to mixing cost (i.e., the increase in reaction time during task blocks that require task switching) on a local-global switching task in young (n = 24) and older (n = 22) adults. Results showed that higher age was associated with widespread increases in RD and decreases in MTR, indicative of white matter deterioration, possibly due to demyelination. Older adults also showed a higher mixing cost, implying slowing of switching performance. Finally, mediation analyses demonstrated that decreases in MTR of the bilateral superior corona radiata contributed to the observed slowing of switching performance with increasing age. These findings provide evidence for a role of cortico-subcortical white matter changes in task switching performance deterioration with healthy aging. Hum Brain Mapp 37:4084-4098, 2016. © 2016 Wiley Periodicals, Inc.

Design of stirred digester with optimization of energy and power consumption

The goal of the present study was to design a new stirred digester according to laboratory experiments. For this purpose, amount of methane produced from co‐digestion of municipal waste, kitchen waste, and cow manure in different treatments was measured in laboratory conditions for 37°C. The substrate characteristics such as both total and volatile solids, pH, EC, amount of total carbon, nitrogen, phosphorus, potassium, and sulfate which can manage the methane production were measured. The results showed that the amounts of these characteristics were in suitable ranges for biogas production. The laboratory experiment results were then used to design an anaerobic digester for single‐family homes based on energy efficiency and mixing cost. As a result, the digester diameter, digester height, slurry height, baffle width, impeller diameter, blade width, blade length, and volume of designed stirred digester were determined as 57, 90, 60, 4.75, 25, 4, 10 cm, and 229 L, respectively. Furthermore, pitched blade turbine with six blades at 45° for speed of 300 rpm not only required a low power but also produced a high torque. Therefore, while the designed biogas plant consumes low energy, it has high mixing cost.Nowadays, the researchers in bio‐system engineering focus on the designing biogas plant according to the direct relation among the power, torque, and energy. The novelty of the article is not only an evaluation of main substrate characteristics on methane production, but also design a new digester with high methane content at suitable pressure based on the best relation among the equipment dimensions of digester determined using shape factors. Furthermore study of impeller types and rotation speeds for providing high torque in low power and reducing energy consumption indirectly, and uses rule of thumb for power consumption to determine the best impeller type and rotation speed. © 2016 American Institute of Chemical Engineers Environ Prog, 36: 104–110, 2017

A hybrid binary particle swarm optimization for large capacitated multi item multi level lot sizing (CMIMLLS) problem

The lot sizing problem deals with finding optimal order quantities which minimizes the ordering and holding cost of product mix. when multiple items at multiple levels with all capacity restrictions are considered, the lot sizing problem become NP hard. Many heuristics were developed in the past have inevitably failed due to size, computational complexity and time. However the authors were successful in the development of PSO based technique namely iterative improvement binary particles swarm technique to address very large capacitated multi-item multi level lot sizing (CMIMLLS) problem. First binary particle Swarm Optimization algorithm is used to find a solution in a reasonable time and iterative improvement local search mechanism is employed to improvise the solution obtained by BPSO algorithm. This hybrid mechanism of using local search on the global solution is found to improve the quality of solutions with respect to time thus IIBPSO method is found best and show excellent results.

Design, calibration and validation of a large lab-scale system for measuring viscosity in fermenting substrate from agricultural anaerobic digesters

European biogas producers are increasingly using lignocellulosic substrates, such as grass. These break down slowly, causing high viscosity in the anaerobic digester slurry, leading to high mixing costs and problems including motor standstill. Unfortunately, viscosity in fibrous slurries is difficult to measure; therefore this work aimed to understand fermenting substrate rheology and to develop a measurement method. A mixing rheometer with a curved impeller was developed to measure the viscosity of fibrous slurries under anaerobic conditions. Using this, the apparent viscosity of fibrous anaerobic-digester content was shown decrease over time (from 5.5–8.5Pas to 3.9–6.0Pas after 2h, γ˙=22s−1). It was confirmed that fibrous anaerobic slurries are shear-thinning fluids that can be described by the power-law, Casson or Bingham models. It was also shown that the shear-thinning behaviour is less pronounced over time. Using two rheoreactors in parallel demonstrated the very large variability in viscosity measurements from a single fibrous sludge, highlighting the need for replicate measurements. A rheoreactor design for measuring the viscosity of fibrous anaerobic sludge and a measurement procedure to take into account the sample variability, as well as changes in viscosity over time and at different shear rates is proposed. This could be used to characterise rheology in many biogas plants, as well as to evaluate the effect of viscosity-reducing treatments.

Optimal Synchronization of a Memristive Chaotic Circuit

This paper deals with the problem of optimal synchronization of two identical memristive chaotic systems. We first study some basic dynamical properties and behaviors of a memristor oscillator with a simple topology. An electronic circuit (analog simulator) is proposed to investigate the dynamical behavior of the system. An optimal synchronization strategy based on the controllability functions method with a mixed cost functional is investigated. A finite horizon is explicitly computed such that the chaos synchronization is achieved at an established time. Numerical simulations are presented to verify the effectiveness of the proposed synchronization strategy. Pspice analog circuit implementation of the complete master-slave-controller systems is also presented to show the feasibility of the proposed scheme.

Electrophysiological correlates of the cognitive control processes underpinning mixing and switching costs

Typically, in task-switching contexts individuals are slower and less accurate when repeating a task in mixed blocks compared to single-task blocks (mixing cost) and when switching to a new task compared to repeating a previous one (switch cost). Previous research has shown that distinct electrophysiological correlates underlie these two phenomena. However, this evidence is not a consistent result. The goal of this study was to better characterize differences between the control processes involved in mixing and switch costs. To this aim, we examined event-related potentials (ERPs) evoked during a cued task-switching experiment. In order to minimize the confounding effects of cognitive demands unrelated to task-switching, we asked participants to shift between two simple tasks (a letter identity task and a letter position task). The mixing cost was defined, in terms of ERPs, by contrasting repeat and single-task trials, whereas the ERP switch cost was obtained from the comparison of switch and repeat trials. Cue-locked ERPs showed that the mixing cost was mediated by two sustained components, an early posterior positivity and a late anterior negativity. On the other hand, the switch cost was associated with two early phasic positive components, one principally distributed over centro-parietal sites and the other located over left posterior sites. In target-locked ERPs the mixing cost was expressed by a frontal positivity, whereas the switch cost was expressed by a reduced parietal P3b. Overall, the results extend previous findings by providing elucidating ERP evidence on distinct proactive and reactive control processes involved in mixing and switch costs.

AN EXPERIMENTAL STUDY ON MUD CONCRETE USING SOIL AS A FINE AGGRGATE AND LD SLAG AS COARSE AGGREGATE

Aggregates are important ingredients of concrete. Sand is used abundantly after air and water. The extensive use of these natural resources is exploiting the environment every day. many alternative materials are being used, viz., slag sand, manufactured sand, quarry dust etc., as fine aggregates; Materials such as steel slag, blast furnace slag are being used as replacement for coarse aggregates. This paper reports the result of different mixes obtained by partial replacement of Natural coarse aggregates (NCA) and complete replacement of fine aggregates (FA) by alternative material such as LD slag and Natural soil respectively. This paper reports the result of different mixes obtained by partial replacement of natural coarse aggregates (CA) and complete replacement of fine aggregates (FA) by alternative material such as LD slag and Natural soil respectively. The wet compressive strength ranged from 16MPa to 20MPa for cubes made of Natural Sand and Natural Coarse Aggregates MIX-D. The wet compressive strength ranged from 18-26MPa for MIX-A; The value obtained for MIX-A was found to be 20% more compared to MIX-D. The split tensile strength ranged from 1.16-1.51MPa for MIX-A, it was concluded that, the mud concrete mix prepared with soil and LD slag gave the satisfactory result which was intended to achieve by normal conventional concrete mix MIX-D. The flexural strength ranged from 3.04-3.41MPa for MIX-A and 2.84-3.45MPa for M4, , it was concluded that, the mud concrete mix prepared with soil and LD slag gave the satisfactory result which was intended to achieve by normal conventional concrete mix. The mud concrete with Soil and LD slag cut down the cost of mix up to 43% when compared with normal conventional concrete of equivalent grade.

Simultaneous interpreters vs. professional multilingual controls: Group differences in cognitive control as well as brain structure and function

There is a vast amount of literature indicating that multiple language expertise leads to positive transfer effects onto other non-language cognitive domains possibly due to enhanced cognitive control. However, there is hardly any evidence about underlying mechanisms on how complex behavior like simultaneous interpreting benefits cognitive functioning in other non-language domains. Therefore, we investigated whether simultaneous interpreters (SIs) exhibit cognitive benefits in tasks measuring aspects of cognitive control compared to a professional multilingual control group. We furthermore investigated in how far potential cognitive benefits are related to brain structure (using voxel-based morphometry) and function (using regions-of-interest-based functional connectivity and graph-analytical measures on low-frequency BOLD signals in resting-state brain data). Concerning cognitive control, the results reveal that SIs exhibit less mixing costs in a task switching paradigm and a dual-task advantage compared to professional multilingual controls. In addition, SIs show more gray matter volume in the left frontal pole (BA 10) compared to controls. Graph theoretical analyses revealed that this region exhibits higher network values for global efficiency and degree and is functionally more strongly connected to the left inferior frontal gyrus and middle temporal gyrus in SIs compared to controls. Thus, the data provide evidence that SIs possess cognitive benefits in tasks measuring cognitive control. It is discussed in how far the central role of the left frontal pole and its stronger functional connectivity to the left inferior frontal gyrus represents a correlate of the neural mechanisms for the observed behavioral effects.

Modulation of Executive Control in the Task Switching Paradigm With Transcranial Direct Current Stimulation (tDCS)

Abstract. Executive processing in the task switching paradigm is primarily associated with activation of the lateral prefrontal cortex (lPFC), demonstrated in numerous functional imaging studies (e.g., Brass & von Cramon, 2002 ). However, there are only very few attempts to modulate neural activation related with executive functions and to investigate the effects of this modulation on the performance in this paradigm. To modulate lPFC activity here, we used the non-invasive transcranial Direct Current Stimulation (tDCS; atDCS [1 mA, 20 min] vs. ctDCS [1 mA, 20 min] vs. sham stimulation [1 mA, 30 s]) over the left inferior frontal junction under conditions of single tasks, task repetitions, and task switches in the task switching paradigm. We assessed the performance effects of online tDCS on mixing costs (single tasks vs. task repetitions) as well as on switching costs (task repetitions vs. task switches). In a within-subjects design across three sessions, there was no evidence of stimulation on the magnitude of these cost types. However, when taking a between-subjects perspective in the first session (i.e., after excluding dominant effects of task experience), atDCS showed an increase in mixing costs in contrast to ctDCS and sham. We interpreted this finding in the context of task switching theories on task activation and task inhibition and their neural localizations.

Inner speech sustains predictable task switching: direct evidence in adults

ABSTRACTIt has been proposed that inner speech supports task selection in task-switching studies, especially when the need for endogenous control is increased. This has been established through the suppression of inner speech in cognitive-flexibility tasks that leads to poorer performance. The aim of this study is to quantify the role of inner speech in a flexibility task by using surface laryngeal electromyography, which, contrary to previous studies, enables participants to freely verbalise the tasks. We manipulated endogenous and exogenous flexibility in a mathematical switching task paradigm. Experiment 1 shows that inner speech acts as a support for switching and is recruited more often when the tasks are of an endogenous type. The main result of Experiment 2 that language is recruited more for the mixing cost than for the switch cost (regardless of the endogenous factor) extends past findings obtained through articulatory suppression.

Age matters: The effect of onset age of video game play on task-switching abilities.

Although prior research suggests that playing video games can improve cognitive abilities, recent empirical studies cast doubt on such findings (Unsworth et al., 2015). To reconcile these inconsistent findings, we focused on the link between video games and task switching. Furthermore, we conceptualized video-game expertise as the onset age of active video-game play rather than the frequency of recent gameplay, as it captures both how long a person has played video games and whether the individual began playing during periods of high cognitive plasticity. We found that the age of active onset better predicted switch and mixing costs than did frequency of recent gameplay; specifically, players who commenced playing video games at an earlier age reaped greater benefits in terms of task switching than did those who started at a later age. Moreover, improving switch costs required a more extensive period of video-game experience than did mixing costs; this finding suggests that certain cognitive abilities benefit from different amounts of video game experience.

Language-switch costs and dual-response costs in bimodal bilingual language production

In communication, different forms of language combinations are possible for bimodal bilinguals, who use a spoken and a signed language. They can either switch from one language to another (language switching) or produce a word and a sign simultaneously (language blending). The present study examines language control mechanisms in language switching and simultaneous bimodal language production, comparing single-response (German or German Sign Language) and dual-response trials (Blend of the German word and the German Sign Language sign). There were three pure blocks, one for each Target-response (German, German Sign Language, Blend), as well as mixed blocks, in which participants switched between all three Target-responses. We observed language mixing costs, switch costs and dual-response costs. Further, the data pattern showed a specific dual-response advantage for switching into a Blend (i.e., a dual-response trial), indicating the specific nature of a blended response in bimodal bilingual language production.

Are simultaneous interpreters expert bilinguals, unique bilinguals, or both?

Simultaneous interpretation is a cognitively demanding process that requires a high level of language management. Previous studies on bilinguals have suggested that extensive practice managing two languages leads to enhancements in cognitive control. Thus, interpreters may be expected to show benefits beyond those seen in bilinguals, either as an extension of previously-seen benefits or in areas specific to interpretation. The present study examined professional interpreters (N = 23) and matched multilinguals (N = 21) on memory tests, the color-word Stroop task, the Attention Network Test, and a non-linguistic task-switching paradigm. The interpreters did not show advantages in conflict resolution or switching cost where bilingual benefits have been noted. However, an interpretation-specific advantage emerged on the mixing cost in the task-switching paradigm. Additionally, the interpreters had larger verbal and spatial memory spans. Interpreters do not continue to garner benefits from bilingualism, but they do appear to possess benefits specific to their experience with simultaneous interpretation.