Static Task Research Articles

Modelling of the Impact of the Retention Reservoir on the Flood Protection of the City – A Case Study for the City of Kalisz (Central Poland)

Floods are natural phenomena related to the circulation of water in nature and they cannot be avoided. Despite the methods of predicting floods, technological development and civilization progress, the flood risk has been still increasing. The relevant hydrotechnical advancement, rational spatial development and optimal water management have a significant impact on reducing the consequences of flooding. Particularly retention reservoirs are decisive to rising flood safety and living conditions of urban residents who are at risk of flooding. The construction of a retention reservoir is a serious engineering, economic and eco-scale challenge. It must be preceded by numerous studies and analyses necessary to carry out the entire construction process and subsequent operation in an optimal way. At present, a number of engineering and environmental analyses are supported by the use of forecasting and computational tools based on the mathematical description of a given physical phenomenon. With their use, it is possible to determine, at the design level, the impact of a technical facility on various elements of the natural or the human environment. The paper presents the impact analyses of a planned retention reservoir located on the Prosna river in the flood protection system in Kalisz (Poland). The flood protection system is insufficient in Kalisz and its weakness was demonstrated, among others, by flood in May, 2010. Analyses were based on data received from the unsteady flow numerical modelling system and optimisation methods to support the management process of retention reservoir resources for extreme periods. The formulated task of dynamic optimisation due to its non-linearity was simplified to a static task by discretisation of an independent variable.

A Scalable and Adaptable ILP-Based Approach for Task Mapping on MPSoC Considering Load Balance and Communication Optimization

Task mapping has been a hot topic in multiprocessor system-on-chip software design for decades. During the mapping process, load balance (LB) and communication optimization have been two important performance optimization factors. This paper studies the relations between LB, interprocessor communications, and communication pipeline technique during the mapping process, and proposes an integer linear programming (ILP)-based static task mapping approach, which considers both LB and communication optimization. The approach consists of an optimized ILP model for task mapping with fewer variables compared to previous ILP mapping works. Moreover, to enhance the scalability of the ILP task mapping, the task-processor-cluster algorithm is proposed to reduce the scale of the task graph and the number of processors and then solve the coarse-grained input by the ILP mapping. To increase the adaptability of the ILP task mapping, the improved augmented $\epsilon $ -constraint method is further integrated with the ILP formulations to select the best mapping for different applications. Experimental results on a 2/4/8/16/24-CPU platform of both synthetic and real-life benchmarks demonstrate the efficiency of the proposed approach.

Optimality of dynamic voltage/frequency scaling in many-core systems with voltage-frequency islands

In today’s multicore systems, depending on an application’s computational demand, cores are either operated individually at different Voltage/Frequency (V/F) levels or grouped into multiple Voltage-Frequency Islands (VFIs) to reduce system energy consumption. This paper formulates a task scheduling and VFI partitioning problem whose optimization goal is to minimize the task set (application) execution time (makespan) for a given energy budget. First, the constrained optimization problem is formulated with integer Linear Programming (ILP) to obtain per-core, per-task dynamic V/F levels in a fine-grain VFI-based system with single-core islands. Next, static task scheduling on coarse-grain VFI-based systems, where an island can contain several cores operated at the same V/F level, is formulated with Mixed integer Linear Programming (MILP), considering the energy budget and task set’s precedence constraints. As an extension of this work and to address varying computational workload of the applications at runtime, this paper proposes a DVFS-enabled VFI system, which forms the VFIs based on the cores’ workload similarities and dynamically adjusts the VFIs’ V/F levels over the applications’ execution phases. The experimental results show that under different energy budget constraints, fine-grain, dynamic task allocations provide on average 1.35x speedup over static coarse-grain scheduling and partitioning methods. Also, the results show that while our dynamically tuned VFI system’s performance is comparable to the fine-grain V/F assignment technique, compared to the static task scheduling/VFI partitioning method, it achieves on average 1.5x speedup across the applications considered in this study.

Tracking Changes in Postural Symmetry Using Pressure Mapping Systems in Children With Cerebral Palsy Receiving Constraint-Induced Movement Therapy (CIMT)

Abstract Date Presented 04/06/19 This research explores how an eight-day CIMT camp improves postural symmetry in children with cerebral palsy. A pressure mapping system was used while participants engaged in functional static and dynamic tasks to assess how improvements in postural symmetry related to functional task performance. Improvements were found in both static sitting and standing tasks. The uses and feasibility of pressure mapping systems within clinical applications will also be explored. Primary Author and Speaker: Aaron Dallman Contributing Authors: Holly Holland, Margo Haynes, Kerry Blazek

Handling Transients of Dynamic Real-Time Workload Under EDF Scheduling

Real-time dynamic workload consists of tasks that can arbitrarily join and leave the system at run-time. To avoid incurring deadline misses, tasks that request to join the system must pass an admission test, which has to cope with potential scheduling transients originated by the residual effect of the tasks that previously left the system. This phenomenon may require some tasks to suffer an admission delay before being accepted for execution. This paper focuses on uniprocessor earliest-deadline first (EDF) scheduling with constrained deadlines and explicitly considers methods for handling scheduling transients in the presence of dynamic real-time workload. A generalized analysis framework is first presented to overcome several limitations of the existing approaches (including the support for overlapping transients), and is then used to derive methods for computing bounds on the admission delays incurred by tasks. Building on such results, an on-line protocol is proposed to handle the admission control of a dynamic workload, which also comes with a variant that can execute in polynomial time to favor its practical application. Furthermore, the paper shows how the presented analysis can be used off-line for analyzing mode-changes among static task sets. Experimental results are finally presented to evaluate the proposed algorithms.

Heterogeneous Multiprocessor Matching Degree Scheduling Algorithm Based on OpenCL Framework

In a heterogeneous multi-core system, the merits of the task scheduling algorithm have a great impact on the efficiency of the system. This paper implements a matching degree scheduling algorithm based on heterogeneous multiprocessor. Before the actual scheduling, the static task feature value and the processor core configuration feature value are mapped into the same European space, and the “program-core-distance” matching value is calculated by using the WED. In the actual scheduling, the matching value and the size of the input byte are obtained, and the tasks are matched with the processor under the influence of the two to determine the execution order of the tasks on each processor. The scheduling method based on OpenCL framework is compared with the traditional scheduling algorithm. It shows that the scheduling scheme implemented in this paper has significantly improved efficiency when executing tasks.

A Heterogeneous Parallel LU Factorization Algorithm Based on a Basic Column Block Uniform Allocation Strategy

Most supercomputers are shipped with both a CPU and a GPU. With the powerful parallel computing capability of GPUs, heterogeneous computing architecture produces new challenges for system software development and application design. Because of the significantly different architectures and programming models of CPUs and GPUs, conventional optimization techniques for CPUs may not work well in a heterogeneous multi-CPU and multi-GPU system. We present a heterogeneous parallel LU factorization algorithm for heterogeneous architectures. According to the different performances of the processors in the system, any given matrix is partitioned into different sizes of basic column blocks. Then, a static task allocation strategy is used to distribute the basic column blocks to corresponding processors uniformly. The idle time is minimized by optimized sizes and the number of basic column blocks. Right-looking ahead technology is also used in systems configured with one CPU core to one GPU to decrease the wait time. Experiments are conducted to test the performance of synchronization and load balancing, communication cost, and scalability of the heterogeneous parallel LU factorization in different systems and compare it with the related matrix algebra algorithm on a heterogeneous system configured with multiple GPUs and CPUs.

Improving Precision Force Control With Low-Frequency Error Amplification Feedback: Behavioral and Neurophysiological Mechanisms.

Although error amplification (EA) feedback has been shown to improve performance on visuomotor tasks, the challenge of EA is that it concurrently magnifies task-irrelevant information that may impair visuomotor control. The purpose of this study was to improve the force control in a static task by preclusion of high-oscillatory components in EA feedback that cannot be timely used for error correction by the visuomotor system. Along with motor unit behaviors and corticomuscular coherence, force fluctuations (Fc) were modeled with non-linear SDA to contrast the reliance of the feedback process and underlying neurophysiological mechanisms by using real feedback, EA, and low-frequency error amplification (LF-EA). During the static force task in the experiment, the EA feedback virtually potentiated the size of visual error, whereas the LF-EA did not channel high-frequency errors above 0.8 Hz into the amplification process. The results showed that task accuracy was greater with the LF-EA than with the real and EA feedback modes, and that LF-EA led to smaller and more complex Fc. LF-EA generally led to smaller SDA variables of Fc (critical time points, critical point of Fc, the short-term effective diffusion coefficient, and short-term exponent scaling) than did real feedback and EA. The use of LF-EA feedback increased the irregularity of the ISIs of MUs but decreased the RMS of the mean discharge rate, estimated with pooled MU spike trains. Beta-range EEG–EMG coherence spectra (13–35 Hz) in the LF-EA condition were the greatest among the three feedback conditions. In summary, amplification of low-frequency errors improves force control by shifting the relative significances of the feedforward and feedback processes. The functional benefit arises from the increase in the common descending drive to promote a stable state of MU discharges.

Head mounted displays for capturing head kinematics in postural tasks

Tracking head motion in a simple, portable and accurate manner during performance of postural tasks in a virtual reality environment could have important implications for investigating normal and pathological head kinematics. We investigated concurrent validity of head tracking of two Head Mounted Displays (HMDs), Oculus Rift and HTC Vive, vs. a gold-standard motion capture system (Qualisys). Head kinematics of N = 20 healthy young adults was quantified during static and dynamic postural tasks. While wearing the Oculus Rift or HTC Vive, participants observed moving stars (static tasks) or a flying ball (dynamic task). Head kinematics were recorded simultaneously by the Rift or Vive and Qualisys camera system. We calculated head directional path, acceleration in 6 directions and volume of translation movement. Intra-Class Correlations (ICC) and 95% Limits of agreement were calculated. Most ICC values were around 0.9 with several at 0.99 indicating excellent agreement between the HMDs and Qualisys. Weaker agreement was observed for vertical displacement during a static task and moderate agreement was observed pitch and yaw displacement during a dynamic task. A negative bias of a small magnitude (indicating more movement in VR) was observed for most variables in static tasks, while a positive bias was observed for most variables in the dynamic task (indicating less movement in VR). Our results generally support the concurrent validity of Oculus Rift and HTC Vive head tracking during static and dynamic standing tasks in healthy young adults. Specific task- and direction-dependent differences should be considered when planning measurement studies using these novel tools.

Dynamic and Static Postural Control in Volleyball Players with Transfemoral Amputation

ABSTRACT Introduction: A decrease in postural control and proprioception is a common result of lower limb amputation. However, postural control adaptation in Paralympic sitting volleyball players with lower limb amputation is not yet understood. Objective: The purpose of this cross-sectional controlled study was to investigate static and dynamic postural control in sitting volleyball players with unilateral transfemoral amputation. Methods: Sixteen subjects participated in the study, eight of whom were amputees with unilateral transfemoral amputation (amputee group: age: 33.5 ± 5.6 years, weight: 77.7 ± 5.3 kg, height: 179.4 ± 5.3 cm) and eight physically active non-amputees (control group age: 27.2 ± 8.4 years, weight: 82.7 ± 6.6 kg, height: 178.7 ± 6.1 cm). Static and dynamic postural control was evaluated using the Neurocom® Balance Master System platform (Modified Clinical Test of Sensory Interaction on Balance, Limits of Stability, Rhythmic Weight Shift, Sit-to-Stand, Walk Across, and Step and Quick Turn). Statistical analyses were performed with the Shapiro-Wilk test, Levene's test, and Student's t-test for paired samples (p <0.05). Results: The amputee group demonstrated impaired postural control in all tests when compared to the control group (p <.05) for all postural tests except for the rhythmic change and sit-to-stand tests (p >.05). Conclusion: Despite training in sitting volleyball, our results demonstrated that amputees have poorer postural control in both static and dynamic tasks when compared to physically active non-amputees. Level of Evidence II; Prognostic Studies—Investigating the Effect of a Patient Characteristic on Disease Outcome / Retrospectivef Study.

The effect of induced fusional demand on static and dynamic stereoacuity thresholds: the digital Synoptophore

Background/aimsThe ability to extract depth from disparity may be hindered under fusional stress, as alignment of the eyes may be more difficult to maintain consistently. Therefore we aim to determine the effect of fusional demand on stereoacuity in individuals with no known binocular vision impairments.MethodsA novel static and dynamic binocular depth detection task, capable of assessing many discrete levels of stereoacuity, was presented on digital displays attached to each tube of the Synoptophore. Stereoacuity was measured with any latent deviation fully corrected and compared to that measured at the ‘recovery’ angle. This recovery angle is where single vision is restored after decompensation to diplopia, during vergence range assessment.ResultsSeventy-two subjects (50 Female, 22 Male; mean (SD) age 22 (6) years) were assessed. The amount of fusional demand was between 1 and 26 prism dioptres (PD), with a mean (SD) of 8(6)PD. Under zero fusion demand the mean (SD) static and dynamic depth detection thresholds were 322(53)” and 69(23)”. Under fusional stress these were 224(40)” and 77(21)”. There was no significant difference between thresholds in stressed and zero demand fusion (p = 0.08). Dynamic depth detection thresholds were significantly lower than static (P < 0.01).ConclusionFusional stress does not appear to impact on stereoacuity. The numerical value of the recovery point varied amongst individuals, but this represents a common point, where single vision is easily restored and binocularity well established. Due to individual differences in the ability to control a certain amount of fusional stress (e.g. vergences stress of 10PD, when recovery is 8PD, will perturb binocularity more than a person with a recovery of 20PD), previous reports may not accurately represent the effect of fusional stress. Whilst our findings are contrary to previous reports, we did not stress fusion beyond the recovery point and used a more accurate/repeatable method to measure stereoacuity.

The Interaction of Compliance and Activation on the Force-Length Operating Range and Force Generating Capacity of Skeletal Muscle: A Computational Study using a Guinea Fowl Musculoskeletal Model.

SynopsisA muscle’s performance is influenced by where it operates on its force–length (F–L) curve. Here we explore how activation and tendon compliance interact to influence muscle operating lengths and force-generating capacity. To study this, we built a musculoskeletal model of the lower limb of the guinea fowl and simulated the F–L operating range during fixed-end fixed-posture contractions for 39 actuators under thousands of combinations of activation and posture using three different muscle models: Muscles with non-compliant tendons, muscles with compliant tendons but no activation-dependent shift in optimal fiber length (L0), and muscles with both compliant tendons and activation-dependent shifts in L0. We found that activation-dependent effects altered muscle fiber lengths up to 40% and increased or decreased force capacity by up to 50% during fixed-end contractions. Typically, activation-compliance effects reduce muscle force and are dominated by the effects of tendon compliance at high activations. At low activation, however, activation-dependent shifts in L0 are equally important and can result in relative force changes for low compliance muscles of up to 60%. There are regions of the F–L curve in which muscles are most sensitive to compliance and there are troughs of influence where these factors have little effect. These regions are hard to predict, though, because the magnitude and location of these areas of high and low sensitivity shift with compliance level. In this study we provide a map for when these effects will meaningfully influence force capacity and an example of their contributions to force production during a static task, namely standing.

Scheduling IoT Healthcare Tasks in Fog Computing Based on their Importance

The Internet-of-Things (IoT) is the future of the Internet and one of the most important technologies used in recent times in all areas, where everything will be connected to the Internet. One of them is using IoT in healthcare area such as mobile health and remote patient monitoring with various diseases such as heart disease, blood pressure, diabetes, and other chronic diseases. The real-time for remote health monitoring applications is very important; any delay caused by transferring data to the cloud and back to the application is unacceptable. So, we propose to use fog computing between sensors and cloud computing to collect and process data in an efficient manner, reduces the amount of data that is transported between the cloud and the sensors, and increase the entire system efficiency. Wireless sensors networks (WSNs) that used in the area of health monitoring send a huge number of tasks with different importance levels and lengths simultaneously to fog computing. Therefore, we need to implement an appropriate task scheduling algorithm with an ability to give priority for tasks accurately and make the main factor in giving priority to tasks is their importance regardless of their length. In this research, we attempt to improve static task scheduling algorithms performance by using a new method called Tasks Classification and Virtual Machines Categorization (TCVC) based on tasks importance. Tasks that received by IoT classified based on their importance into three classes: high importance tasks, medium importance tasks, and low importance tasks based on the patient’s health status. In order to measure the performance achieved by these methods, they will be applied on MAX-MIN scheduling algorithm. The cloudsim simulator has been used to measure their impact on algorithm complexity, resource availability, Total Execution Time (TET), Total Waiting Time (TWT), and Total Finish Time (TFT).

Exploration of two safety strategies in human-robot collaborative manufacturing using Virtual Reality

“beWare of the Robot” is a custom-designed Virtual Reality application and implemented as a platform for simulating in real-time Human-Robot collaboration in manufacturing tasks. This work reports on its use for investigating two alternative safe collaboration strategies, namely ‘Reduce Speed’ and ‘Move Back’, in the task of handling fabric when building aerospace composite material parts. Both methods are triggered when the distance of the human to the robot falls below a certain threshold. Experimentation was conducted in live tests, taking into account pressure and force thresholds regarding painful transient contact of the robot with the human following ISO/TS 15066:2016. Indices such as mean robot speed, time of collaboration, number and severity of collisions, were recorded in order to assess and ‘tweak’ these methods. Tweaking involved speed reduction factor in ‘Reduce Speed’ and waiting time after completion of stationary tasks in both strategies. Visual cues in terms of graded coloured robot motion volume to indicate varying interference of the human proved ineffective. Beyond statistical assessment of safe collaboration strategies, qualitative assessment was provided by the experiment participants according to acquired experience.

An Innovative Approach for Ad Hoc Network Establishment in Disaster Environments by the Deployment of Wireless Mobile Agents

In disasters, many stationary tasks, such as saving survivors in debris, extinguishing fire of buildings, and so on, need first responders to complete on site. In such circumstances, wireless mobile robots are usually employed to search for tasks and establish ad hoc networks to assist first responders. Due to the unknown and complexity of environments and limited capabilities of wireless mobile robots, searching and establishing ad hoc networks in disaster environments is a challenging issue in both theory and practice. To this end, a task-based wireless mobile robot deployment approach is proposed in this article. The proposed approach consists of a search process and a deployment process. The search process can guide wireless mobile robots to efficiently find tasks in unknown and complex environments. The deployment process can find suitable deployment locations for wireless mobile robots to establish ad hoc networks. The established ad hoc networks can ensure the communication of wireless mobile robots in the network and can cover the maximum number of task locations and the maximum areas in a disaster environment. Experimental results demonstrate that based on the proposed approach, wireless mobile robots have better performance in terms of search and ad hoc network establishment in disaster environments.

Human/robotic interaction: vision limits performance in simulated vitreoretinal surgery.

Compare accuracy and precision in XYZ of stationary and dynamic tasks performed by surgeons with and without the use of a tele-operated robotic micromanipulator in a simulated vitreoretinal environment. The tasks were performed using a surgical microscope or while observing a video monitor. Two experienced and two novice surgeons performed tracking and static tasks at a fixed depth with hand-held instruments on a Preceyes Surgical System R0.4. Visualization was through a standard microscope or a video display. The distances between the instrument tip and the targets (in μm) determined tracking errors in accuracy and precision. Using a microscope, dynamic or static accuracy and precision in XY (planar) movements were similar among test subjects. In Z (depth) movements, experience lead to more precision in both dynamic and static tasks (dynamic 35±14 versus 60±37μm; static 27±8 versus 36±10μm), and more accuracy in dynamic tasks (58±35 versus 109±79μm). Robotic assistance improved both precision and accuracy in Z (1-3±1μm) in both groups. Using a video screen in combination with robotic assistance improved all performance measurements and reduced any differences due to experience. Robotics increases precision and accuracy, with greater benefit observed in less experienced surgeons. However, human control was a limiting factor in the achieved improvement. A major limitation was visualization of the target surface, in particular in depth. To maximize the benefit of robotic assistance, visualization must be optimized.

Work-Related Musculoskeletal Disorders, Occupational Stress, and Their Associations with General Health in Working Populations in Various Industries

Background: Work-related musculoskeletal disorders (WMSDs) have been documented in various occupational groups in Iran. However, there is a gap in the studies regarding the prevalence of WMSDs, occupational stress, and general health in workers. The present study aimed to investigate the correlations between WMSDs, occupational stress, and general health. Methods: This cross-sectional study was conducted on 455 workers selected from various industries in 10 cities in Iran. Data were collected using self-reported measures to evaluate the body map, HSE management standards indicator tool, and general health questionnaire (GHQ). Results: In total, 455 questionnaires were completed and analyzed. The mean differences were compared using the Kruskal-Wallis test. The results of Spearman's correlation-coefficient indicated a significant, positive correlation between WMSDs and occupational stress. In addition, negative correlations were observed between general health, WMSDs, and occupational stress. Conclusion: Some of the recommendations based on the findings are modifying the workplaces of individuals who perform long-term, static tasks, periodic identification of the individuals with musculoskeletal problems and taking measures to correct their posture, designing proper physical exercises for the individuals with hard work postures, and cognitive-behavioral education to raise awareness regarding the complications of mental health problems.

Haptic programming in construction

Industrial robotics currently focuses on the utilization within clearly defined production environments. A paradigm shift away from repetition of static tasks towards dynamic human–robot collaboration is noticeable, specifically due to developments triggered by Industry 4.0 concepts. Within construction industries static automation can only be achieved at a prefabrication level; through these new developments adaptable robotics can be utilized for new concepts of on-site robotic assistance. Within this paper, we illustrate our approach towards robotics that adapts to changing environmental conditions and material features. Simultaneously we take advantage of existing pre-planning methods within computer-aided design (CAD). In order to take full advantage of the mixed human and machine work environments within construction, we enable on-site adaptation towards a pre-planned assembly strategy. We show our applications within the assembly of complex timber structures as well as transfer of the concept towards other construction tasks. By combining a priori knowledge from the design phase with haptic interaction primitives, we enable intuitive human–robot collaboration. For this approach the term of haptic programming was coined, which allows the exchange of knowledge between the user and a robot on a physical level.

Investigating the impact of dynamic and static secondary tasks on task-switch cost.

Many researchers have employed secondary tasks, which have to be performed in parallel with a primary task requirement, to examine how successful task selection is accomplished in the context of task switching. The influence of such a secondary task on the observed switch cost (i.e., the cost arising when the currently relevant task differs from the task performed most recently) is seen as indicative that cognitive processes such as self-instruction are involved. Most secondary tasks chosen so far have required the repeated utterance of a word or syllable or a rhythmic movement of the foot. In the present study, we manipulated the dynamics of the to-be-performed secondary task (i.e., a repeated utterance or movement, or a static task that involved similar muscles-holding a spattle in the mouth or pressing keys). Additionally, we tested for modality-specific influences by asking participants to perform a dynamic or nondynamic (i.e., static) secondary task with two effector systems, namely oral and manual. Overall, our secondary tasks led to a reduced (rather than an increased) switch cost, as compared to a control condition without any secondary task. This reduction in switch cost was dependent on the secondary-task dynamics but independent of the effectors involved, showing larger switch-cost reductions for dynamic secondary tasks. To explain this finding, we suggest that performing secondary tasks interferes with the formation of episodic-memory traces that would lead to retrieval benefits in the case of a task repetition, so that our reduced task-switch costs actually represent reduced repetition benefits.

Potential Mechanisms of Sensory Augmentation Systems on Human Balance Control.

Numerous studies have demonstrated the real-time use of visual, vibrotactile, auditory, and multimodal sensory augmentation technologies for reducing postural sway during static tasks and improving balance during dynamic tasks. The mechanism by which sensory augmentation information is processed and used by the CNS is not well understood. The dominant hypothesis, which has not been supported by rigorous experimental evidence, posits that observed reductions in postural sway are due to sensory reweighting: feedback of body motion provides the CNS with a correlate to the inputs from its intact sensory channels (e.g., vision, proprioception), so individuals receiving sensory augmentation learn to increasingly depend on these intact systems. Other possible mechanisms for observed postural sway reductions include: cognition (processing of sensory augmentation information is solely cognitive with no selective adjustment of sensory weights by the CNS), “sixth” sense (CNS interprets sensory augmentation information as a new and distinct sensory channel), context-specific adaptation (new sensorimotor program is developed through repeated interaction with the device and accessible only when the device is used), and combined volitional and non-volitional responses. This critical review summarizes the reported sensory augmentation findings spanning postural control models, clinical rehabilitation, laboratory-based real-time usage, and neuroimaging to critically evaluate each of the aforementioned mechanistic theories. Cognition and sensory re-weighting are identified as two mechanisms supported by the existing literature.