Optimal Scheduling Using Branch and Bound with SPIN 4.0

The use of model checkers to solve discrete optimisation problems is appealing. A model checker can first be used to verify that the model of the problem is correct. Subsequently, the same model can be used to find an optimal solution for the problem. This paper describes how to apply the new PROMELA primitives of SPIN 4.0 to search effectively for the optimal solution. We show how Branch-and-Bound techniques can be added to the LTL property that is used to find the solution. The LTL property is dynamically changed during the verification. We also show how the syntactical reordering of statements and/or processes in the PROMELA model can improve the search even further. The techniques are illustrated using two running examples: the Travelling Salesman Problem and a job-shop scheduling problem

Verification and Optimization of a PLC Control Schedule

We report on the use of the SPIN model checker for both the verification of a process control program and the derivation of optimal control schedules. This work was carried out as part of a case study for the EC VHS project (Verification of Hybrid Systems), in which the program for a Programmable Logic Controller (PLC) of an experimental chemical plant had to be designed and verified. The intention of our approach was to see how much could be achieved here using the standard model checking environment of SPIN/Promela. As the symbolic calculations of real-time model checkers can be quite expensive it is interesting to try and exploit the efficiency of established non-real-time model checkers like SPIN in those cases where promising work-arounds seem to exist. In our case we handled the relevant real-time properties of the PLC controller using a time-abstraction technique; for the scheduling we implemented in Promela a so-called variable time advance procedure. For this case study these techniques proved sufficient to verify the design of the controller and derive (time-)optimal schedules with reasonable time and space requirements

Staging Laparoscopy for Hilar Cholangiocarcinoma: Is it Still Worthwhile?

This study was designed to evaluate the benefit of staging laparoscopy (SL) in patients with suspected hilar cholangiocarcinoma (HCCA) during the past 10 years. Only 50-60% of patients with HCCA who undergo laparotomy are ultimately amenable to a potentially curative resection. In a previous study, we recommended routine use of SL to prevent unnecessary laparotomies. The accuracy of imaging techniques, however, has significantly improved during the past decade, which is likely to impact the yield and accuracy of SL. From 2000 to 2010, 195 patients with suspected HCCA were analyzed. The yield and accuracy of SL were calculated by dividing total number of avoided laparotomies by the total number of laparoscopies or by all patients with unresectable disease, respectively. Factors associated with better yield and accuracy were assessed. Of 195 patients with HCCA, 175 underwent SL. The yield of SL was 14% and the accuracy was 32%. Operative morbidity of SL was 3%, and operative morbidity of laparotomy for unresectable disease was 33%. No clear factors that influenced the yield of SL were found. Overall yield and accuracy of SL for HCCA in the present series decreased to 14% and 32%, respectively, compared with earlier reports. This finding is likely the result of improved imaging techniques that evolved during the past decade. The place of SL in the workup of patients with HCCA needs to be reconsidered, and one should decide whether the declining additional value of SL still outweighs the drawbacks of S

Metal-polymer functionally graded materials for removing guided wave reflections at beam end boundaries

This paper investigates the potential of a metal-polymer functionally graded material (FGM) to remove beam end boundary wave reflections that produce complicated interference patterns in the response signals used for guided wave damage identification methodologies. The metal-polymer FGM matches the material properties to a metal beam for total wave transmission on one side and is continuously graded to a viscoelastic polymer on the other side. An Aluminium-Polycarbonate (Al-PC) FGM was fabricated and characterised using microscopy, hardness testing and through-transmission ultrasonics to verify the continuous gradient. Measurements of guided waves on an aluminium beam attached to the FGM on one end show reduction in boundary wave reflections that varies with wave frequency. A damaged aluminium beam attached with the FGM produced promising improvements in a damage identification system

The effect of abdominal functional electrical stimulation on bowel function in multiple sclerosis: a cohort study

Background: Chronic constipation is prevalent in people with multiple sclerosis, with current treatments usually only partially effective. Objectives: This study aims to evaluate the efficacy of abdominal functional electrical stimulation to reduce whole gut and colonic transit times and improve bowel and bladder-related quality of life. Methods: A total of 23 people with multiple sclerosis who fulfilled the Rome III criteria for functional constipation applied abdominal functional electrical stimulation for 1 hour per day, 5 days per week, for 6 weeks. Whole gut and colonic transit times and bowel and bladder-related quality of life were measured before and after the intervention period. Results: Whole gut (mean 81.3 (standard deviation 28.7) hours pre vs. 96.1 (standard deviation 53.6) hours post-intervention, P = 0.160) and colonic transit time (65.1 (31.4) vs. 74.8 (51.1) hours, P = 0.304) were unchanged following 6 weeks of abdominal functional electrical stimulation. There was a significant improvement in bowel (mean 1.78 (SD: 0.64) pre vs. 1.28 (SD: 0.54) post, P = 0.001) and bladder (50.6 (26.49) vs. 64.5 (21.92), p = 0.007) related quality of life after the intervention period. Conclusion: While abdominal functional electrical stimulation did not reduce whole gut and colonic transit times for people with multiple sclerosis, a significant improvement in bowel and bladder-related quality of life was reported

The frequency of bowel and bladder problems in multiple sclerosis and its relation to fatigue: A single centre experience

Background Bowel and bladder problems affect more than 50% of people with Multiple Sclerosis (MS). These problems have a large impact on quality of life and place a significant burden on health systems. Objectives This study aimed to ascertain the frequency of bladder and bowel problems in a select Australian MS cohort and to investigate the relationships between level of disability, bladder and bowel problems, and fatigue. Methods Questionnaires on the nature and severity of MS symptoms were distributed to clients attending an Australian MS centre. Log-binomial regression and multiple linear regression models were used to investigate relationships between disability, fatigue, and bladder and bowel problems. Results and conclusions Of 167 questionnaires distributed, 136 were completed. Bladder problems were reported by 87 (74.4%) respondents, whilst 66 (48.9%) experienced functional constipation and 43 (31.9%) faecal incontinence. This frequency in our select Australian MS population is similar to that reported globally. There was a significant correlation between level of disability and: bladder problems (p = 0.015), faecal incontinence (p = 0.001), fatigue (p<0.001) and constipation (p = 0.016, relative risk: 1.16). Further investigation into the causal relationships between various MS symptoms may be beneficial in the development of novel therapeutic strategies for people with MS

Application profiling and resource management for MapReduce

Scale of data generated and processed is exponential growth in the Big Data ear. It poses a challenge that is far beyond the goal of a single computing system. Processing such vast amount of data on a single machine is impracticable in term of time or cost. Hence, distributed systems, which can harness very large clusters of commodity computers and processing data within restrictive time deadlines, are imperative. In this thesis, we target two aspects of distributed systems: application profiling and resource management. We study a MapReduce system in detail, which is a programming paradigm for large scale distributed computing, and presents solutions to tackle three key problems. Firstly, this thesis analyzes the characteristics of jobs running on the MapReduce system to reveal the problem—the Application scope of MapReduce has been extended beyond the original design goal that was large-scale data processing. This problem enables us to present a Workload Characteristic Oriented Scheduler (WCO), which strives for co-locating tasks of possibly different MapReduce jobs with complementing resource usage characteristics. Secondly, this thesis studies the current job priority mechanism focusing on resource management. In the MapReduce system, job priority only exists at scheduling level. High priority jobs are placed at the front of the scheduling queue and dispatched first. Resource, however, is fairly shared among jobs running at the same worker node without any consideration for their priorities. In order to resolve this, this thesis presents a non-intrusive slot layering solution, which dynamically allocates resource between running jobs based on their priority and efficiently reduces the execution time of high priority jobs while improves overall throughput. Last, based on the fact of underutilization of resource at each individual worker node, this thesis propose a new way, Local Resource Shaper (LRS), to smooth resource consumption of each individual job by automatically tuning the execution of concurrent jobs to maximize resource utilization while minimizing resource contention

Optimal Scheduling Using Branch and Bound with SPIN 4.0

The use of model checkers to solve discrete optimisation problems is appealing. A model checker can first be used to verify that the model of the problem is correct. Subsequently, the same model can be used to find an optimal solution for the problem. This paper describes how the new Promela primitives of Spin 4.0 can be applied to search e#ectively for the optimal solution. We show how Branch-and-Bound techniques can be added to the LTL property that is used to find the solution. The LTL property is dynamically changed during the verification