Hierarchical Scheduling of an SDF/L Graph onto Multiple Processors

Although dataflow models are known to thrive at exploiting task-level parallelism of an application, it is difficult to exploit the parallelism of data, represented well with loop structures, since these structures are not explicitly specified in existing dataflow models. SDF/L model overcomes this shortcoming by specifying the loop structures explicitly in a hierarchical fashion. We introduce a scheduling technique of an application represented by the SDF/L model onto heterogeneous processors. In the proposed method, we explore the mapping of tasks using an evolutionary meta-heuristic and schedule hierarchically in a bottom-up fashion, creating parallel loop schedules at lower levels first and then re-using them when constructing the schedule at a higher level. The efficiency of the proposed scheduling methodology is verified with benchmark examples and randomly generated SDF/L graphs.

Analisis Human Error dengan Pendekatan Metode SHERPA dan HEART pada Produksi Batu Bata UKM Yasin

Kesalahan kerja yang terjadi banyak diakibatkan oleh manusia itu sendiri yang disebut dengan human error. Human error yang sering terjadi dalam kegiatan produksi bisa merugikan perusahaan dalam mewujudkan efektivitas dan efisiensi produksi. Oleh karena itu maka perlu dilakukan perbaikan performansi pekerja untuk mengurangi seringnya terjadi kesalahan kerja. Beberapa metode dalam mengidentifikasi human error diantaranya metode SHERPA dan HEART. SHERPA suatu metode kualitatif dalam menganalisis human error yang menjadikan task level sebagai dasar inputnya. Sedangkan HEART adalah metode dalam menentukan resiko human error yang cepat, sederhana dan gampang dimengerti oleh para engineers dan juga human factors specialists. UKM Yasin merupakan salah satu UKM yang bergerak dalam produksi batu bata di Kota Batam. Proses pembuatan batu bata melalui beberapa tahapan yaitu proses pencetakan, proses pengeringan dan proses pembakaran. Permasalahan yang masih sering terjadi yaitu kesalahan saat melakukan pekerjaan yang berakibat terhadap kecelakaan kerja dan juga berpengaruh terhadap output produksi batu bata, hal ini disebabkan oleh human error. Hasil penelitian untuk rekomendasi yang akan diperlukan untuk mereduksi error pada proses produksi batu bata dengan metode SHERPA yaitu melakukan pemeriksaan secara teliti dan rutin terhadap masing-masing proses dan memberikan pelatihan secara berkala terhadap pekerja. Peluang terjadinya error dalam setiap aktivitas pekerjaan pada produksi batu bata dengan menggunakan metode HEART dimana nilai human error probability yang paling besar yaitu 0.16. Proses yang mungkin terjadinya human error dalam tahapan proses produksi batu bata di UKM Yasin melalui nilai Human Error Probability (HEP) tertinggi yaitu 0.544 yang terdapat pada proses pembakaran batu bata.

Computational validity: using computation to translate behaviours across species

We propose a new conceptual framework (computational validity) for translation across species and populations based on the computational similarity between the information processing underlying parallel tasks. Translating between species depends not on the superficial similarity of the tasks presented, but rather on the computational similarity of the strategies and mechanisms that underlie those behaviours. Computational validity goes beyond construct validity by directly addressing questions of information processing. Computational validity interacts with circuit validity as computation depends on circuits, but similar computations could be accomplished by different circuits. Because different individuals may use different computations to accomplish a given task, computational validity suggests that behaviour should be understood through the subject's point of view; thus, behaviour should be characterized on an individual level rather than a task level. Tasks can constrain the computational algorithms available to a subject and the observed subtleties of that behaviour can provide information about the computations used by each individual. Computational validity has especially high relevance for the study of psychiatric disorders, given the new views of psychiatry as identifying and mediating information processing dysfunctions that may show high inter-individual variability, as well as for animal models investigating aspects of human psychiatric disorders. This article is part of the theme issue ‘Systems neuroscience through the lens of evolutionary theory’.

Project Portfolio Selection and Scheduling with Resource Allocation, Synergies, and Project Divisibility

A project portfolio can be defined as a set of project proposals that are selected according to one or more criteria by a decision-maker (individual or group). Regularly, the portfolio selection involves different decision problems, among those evaluation, selection, scheduling, and resource allocation. In published scientific literature, these problems have been addressed mainly separately giving as a result suboptimal solutions (portfolios). In addition, elements as partial allocation and project representation through tasks constitute relevant characteristics in practice that remain unaddressed in depth. The proposal of this research is to integrate the project selection and project scheduling, incorporating all relevant elements of both decision problems through the scheduling of tasks allowing to determine when the task will be funded and executed. The main impact of precedence rules at the task level in the portfolio is also studied. In this work, Project Portfolio Selection and Scheduling Problem (PPSS) is studied and solved through a new mixed-integer linear programming (MILP) model. The model incorporates renewable and nonrenewable resource allocation, along with partial and total funding policies, project divisibility, and interdependences. Scheduling is integrated into the model, both at the project level and at the project task level, which allows scheduling in noncontiguous periods. Small instances (up to 64 projects) and medium instances (up to 128 projects) were solved optimally in very short times. The relationship between the quality of near-optimal solutions and the solution computing time by modifying the parameters of the solver employed was researched. No significant change in the solution’s quality was perceived, but a significant reduction in solution computing time was achieved. Furthermore, the main effects of precedence rules on solution times and portfolio impact were studied. Results show that even if few precedence rules were introduced, the resource allocation of tasks changed significantly, even though the portfolio impact or the number of projects of the selected portfolios remains the same.

Neurophysiological Verbal Working Memory Patterns in Children: Searching for a Benchmark of Modality Differences in Audio/Video Stimuli Processing

Exploration of specific brain areas involved in verbal working memory (VWM) is a powerful but not widely used tool for the study of different sensory modalities, especially in children. In this study, for the first time, we used electroencephalography (EEG) to investigate neurophysiological similarities and differences in response to the same verbal stimuli, expressed in the auditory and visual modality during the n-back task with varying memory load in children. Since VWM plays an important role in learning ability, we wanted to investigate whether children elaborated the verbal input from auditory and visual stimuli through the same neural patterns and if performance varies depending on the sensory modality. Performance in terms of reaction times was better in visual than auditory modality ( p = 0.008) and worse as memory load increased regardless of the modality ( p < 0.001). EEG activation was proportionally influenced by task level and was evidenced in theta band over the prefrontal cortex ( p = 0.021), along the midline ( p = 0.003), and on the left hemisphere ( p = 0.003). Differences in the effects of the two modalities were seen only in gamma band in the parietal cortices ( p = 0.009). The values of a brainwave-based engagement index, innovatively used here to test children in a dual-modality VWM paradigm, varied depending on n-back task level ( p = 0.001) and negatively correlated ( p = 0.002) with performance, suggesting its computational effectiveness in detecting changes in mental state during memory tasks involving children. Overall, our findings suggest that auditory and visual VWM involved the same brain cortical areas (frontal, parietal, occipital, and midline) and that the significant differences in cortical activation in theta band were more related to memory load than sensory modality, suggesting that VWM function in the child’s brain involves a cross-modal processing pattern.

The relationship between physiological arousal and multiple levels of temporal context in risky choice

Context-dependence is fundamental to risky monetary decision-making. A growing body of evidence suggests that temporal context, or recent events, alters risk-taking at a minimum of three timescales: immediate (e.g. trial-by-trial), neighborhood (e.g. a group of consecutive trials), and global (e.g. task-level). To examine context effects, we created a novel monetary choice set with intentional temporal structure in which option values shifted between multiple levels of value magnitude (“contexts”) several times over the course of the task. This structure allowed us to examine whether effects of each timescale were simultaneously present in risky choice behavior and the potential mechanistic role of arousal, an established correlate of risk-taking, in context-dependency. We found that risk-taking was sensitive to immediate, neighborhood, and global timescales, increasing following small (vs. large) outcome amounts, large positive (but not negative) shifts in context, and when cumulative earnings exceeded expectations. We quantified arousal with skin conductance responses, which were specifically related to the global timescale, increasing with cumulative earnings, suggesting that physiological arousal captures a task-level assessment of performance. We complimented this correlational analysis with a secondary reanalysis of risky monetary choices following the double-blind administration of propranolol and a placebo during a temporally unstructured choice task. We replicated our behavioral finding that risk-taking is context-sensitive at three timescales but found no change in temporal context-effects following propranolol administration. Our results demonstrate that risky decision-making is consistently dynamic at multiple timescales and that arousal is likely the consequence, rather than the cause, of temporal context in risky monetary decision-making.

Task-Level Authoring for Remote Robot Teleoperation

Remote teleoperation of robots can broaden the reach of domain specialists across a wide range of industries such as home maintenance, health care, light manufacturing, and construction. However, current direct control methods are impractical, and existing tools for programming robot remotely have focused on users with significant robotic experience. Extending robot remote programming to end users, i.e., users who are experts in a domain but novices in robotics, requires tools that balance the rich features necessary for complex teleoperation tasks with ease of use. The primary challenge to usability is that novice users are unable to specify complete and robust task plans to allow a robot to perform duties autonomously, particularly in highly variable environments. Our solution is to allow operators to specify shorter sequences of high-level commands, which we call task-level authoring, to create periods of variable robot autonomy. This approach allows inexperienced users to create robot behaviors in uncertain environments by interleaving exploration, specification of behaviors, and execution as separate steps. End users are able to break down the specification of tasks and adapt to the current needs of the interaction and environments, combining the reactivity of direct control to asynchronous operation. In this paper, we describe a prototype system contextualized in light manufacturing and its empirical validation in a user study where 18 participants with some programming experience were able to perform a variety of complex telemanipulation tasks with little training. Our results show that our approach allowed users to create flexible periods of autonomy and solve rich manipulation tasks. Furthermore, participants significantly preferred our system over comparative more direct interfaces, demonstrating the potential of our approach for enabling end users to effectively perform remote robot programming.