Performance of distributed mechanisms for flow admission in wireless adhoc networks

Given a wireless network where some pairs of communication links interfere with each other, we study sufficient conditions for determining whether a given set of minimum bandwidth quality-of-service (QoS) requirements can be satisfied. We are especially interested in algorithms which have low communication overhead and low processing complexity. The interference in the network is modeled using a conflict graph whose vertices correspond to the communication links in the network. Two links are adjacent in this graph if and only if they interfere with each other due to being in the same vicinity and hence cannot be simultaneously active. The problem of scheduling the transmission of the various links is then essentially a fractional, weighted vertex coloring problem, for which upper bounds on the fractional chromatic number are sought using only localized information. We recall some distributed algorithms for this problem, and then assess their worst-case performance. Our results on this fundamental problem imply that for some well known classes of networks and interference models, the performance of these distributed algorithms is within a bounded factor away from that of an optimal, centralized algorithm. The performance bounds are simple expressions in terms of graph invariants. It is seen that the induced star number of a network plays an important role in the design and performance of such networks.Comment: 21 pages, submitted. Journal version of arXiv:0906.378

Reliability and Validity of a Modified PHQ-9 Item Inventory (PHQ-12) as a Screening Instrument for Assessing Depression in Asian Indians (CURES - 65)

Abstract Objectives: To evaluate the validity and reliability of the modified Patient Health Questionnaire(PHQ) 12 item instrument as a screening tool for assessing depression compared to the PHQ -9 in a representative south Indian urban population. Methods: The Chennai Urban Rural Epidemiology Study [CURES] is a large cross-sectional study conducted in Chennai, South India. In Phase 1 of CURES(urban component), 26,001 individuals aged ≥ 20 years individuals were selected by a systematic sampling technique of whom one hundred subjects were randomly selected, using computer-generated numbers, for this validation study. Two self-reported questionnaires (modified PHQ-12 item and PHQ 9 item) were administered to the subjects to compare their effectiveness in detecting depression. Reliability and validity were assessed and Receiver Operating Characteristic (ROC) curves were plotted. Pearson’s correlation was used to compare the two questionnaires. Results: The mean age of the study was 38.6±11.6 years and 48% were males. Pearson’s correlation coefficient between the modified PHQ-12 and the PHQ-9 item was 0.913 [p<0.0001]. Factor Analysis revealed that the modified PHQ 12 item scale can be used as a unidimensional scale and had excellent internal consistency(Cronbach’s alpha:0.88). A cut point of >4 calculated using the ROC curves for the modified PHQ- 12 item had the highest sensitivity (92.0%) and specificity (90.7%) using PHQ-9 as the gold standard. The positive predictive value was 76.7%, and the negative predictive value, 97.1% and the area under the ROC curve, 0.979 (95% Confidence Interval: 0.929 - 0.997, p<0.0001). Conclusion: The modified PHQ-12 item is a valid and reliable instrument for large scale population based screening of depression in Asian Indians and a cut point score of 4 or greater gave the highest sensitivity and specificity.

Measurement Of Film Thickness And Temperature On Horizontal Metal Spray Coated Tube Falling Film Evaporator Using Interferometric Techique

’Water’ is the ’Essence of Life’. It is an irreplaceable precious resource that is core of life on earth, a vital commodity that is critical for human survival, socio-economic developments and for the preservation of a healthy ecosystem. Current trends indicate that two-thirds of the world’s population will be living in water-stressed countries by 2025(wat (2006)). In order to eradicate or to provide sufficient water requirement for mankind desalination plays a pivotal role. This paper presents studies on horizontal tube falling film evaporator for Multi effect desalination (MED) system with spray coated tubes. The most important component in any MED system is the falling film evaporator. The wide acceptance for this kind of evaporators is because of the fact that it is characterized by a very low-pressure drop. In MED systems, falling film evaporation takes place outside the tube geometry utilizing the latent heat of condensing vapour inside the tube. Convective evaporation, as well as low-temperature nucleate boiling, occur in the film as it flows over the tube depending on the operating conditions(Abraham and Mani (2015)). The liquid falls on the top of the tube and flows down along the curved tube surface. There is a phase change on both sides of the tube and the evaporation outside the tube helps vapour to be separated from the liquid as soon as it is formed. Two different tubes surfaces were studied, namely bare copper tube and copper tube coated with alloy of Al2O3 and TiO2. Scanning electron microscope, Energy-dispersive X-ray spectroscopy, 3D surface profilometer were utilized to study about the surface texture, composition and to find surface roughness values attributed with each tubes. An optical shadow method (non-intrusive) incorporating Otsus’s algorithm was used to evaluate the film thickness around the circumference of the cylinder, and a Mach-Zehnder Interferometer (MZI) was employed to visualize the isotherm formation (Maliackal et al. (2021)). All studies were performed for complete wetting of the tube. The measured film thickness was compared with commonly used empirical formulas. Further, the effectiveness of using those empirical formulas for small diameter tubes was analyzed. A novel interferometric technique was used to analyze the film interface temperature, and a comparative study was performed for the two different tube geometries. A standard error of mean (SEM) analysis was performed on every data set

PLC – HMI Automation Based Cascaded Fuzzy PID for Efficient Energy Management and Storage in Real Time Performance of a Hydro Electric Pumped Storage Power Plant

AbstractUsually in order to balance the load demand at high peak hours, hydro electric pumped storage power plant is utilized. In this project a novel design, (CFPID) Cascaded Fuzzy PID (Proportional - Integral - Derivative) controller scheme using B&R (Bernecker & Rainer) Industrial Automation PLC - HMI (Programmable Logic Control - Human Machine Interface) for Efficient Energy management and storage in real time performance of a hydro electric pumped storage power plant is proposed. In this scheme, Fuzzy Level is cascaded with PID Flow for improvement in performance. A prototype model of a hydro electric pumped storage power plant with 22 digital inputs and 14 potential free outputs is fabricated with an objective of controlling the process variables, flow and level is done by using conventional PLC and the proposed CFPID control. There are two tanks in the prototype, lower tank with 2 stages of level and upper tank with 5 stages of level. HMI is used to monitor and operate the process in online - real time, for easy control of the operations. In this paper, the proposed PLC- HMI automation based CFPID control scheme is performed and finally compared with the conventional PLC by experimental results and validated by using real time statistics obtained from the hydro electric pumped storage power plant

Adaptive Alert Management for Balancing Optimal Performance among Distributed CSOCs using Reinforcement Learning

Large organizations typically have Cybersecurity Operations Centers (CSOCs) distributed at multiple locations that are independently managed, and they have their own cybersecurity analyst workforce. Under normal operating conditions, the CSOC locations are ideally staffed such that the alerts generated from the sensors in a work-shift are thoroughly investigated by the scheduled analysts in a timely manner. Unfortunately, when adverse events such as increase in alert arrival rates or alert investigation rates occur, alerts have to wait for a longer duration for analyst investigation, which poses a direct risk to organizations. Hence, our research objective is to mitigate the impact of the adverse events by dynamically and autonomously re-allocating alerts to other location(s) such that the performances of all the CSOC locations remain balanced. This is achieved through the development of a novel centralized adaptive decision support system whose task is to re-allocate alerts from the affected locations to other locations. This re-allocation decision is non-trivial because the following must be determined: (1) timing of a re-allocation decision, (2) number of alerts to be re-allocated, and (3) selection of the locations to which the alerts must be distributed. The centralized decision-maker (henceforth referred to as agent) continuously monitors and controls the level of operational effectiveness-LOE (a quantified performance metric) of all the locations. The agent's decision-making framework is based on the principles of stochastic dynamic programming and is solved using reinforcement learning (RL). In the experiments, the RL approach is compared with both rule-based and load balancing strategies. By simulating real-world scenarios, learning the best decisions for the agent, and applying the decisions on sample realizations of the CSOC's daily operation, the results show that the RL agent outperforms both approaches by generating (near-) optimal decisions that maintain a balanced LOE among the CSOC locations. Furthermore, the scalability experiments highlight the practicality of adapting the method to a large number of CSOC locations

Dietary Salt Intake and Hypertension in An Urban South Indian Population – [CURES - 53]

Objective : The aim of the study was to determine the mean dietary salt intake in urban south India and to look at its association with hypertension. Methods : The Chennai Urban Rural Epidemiology Study (CURES) is an ongoing population based study on a representative population of Chennai city in southern India. Phase 1 of CURES recruited 26,001 individuals aged ≥ 20 years, of whom every tenth subject (n=2600) was invited to participate in Phase 3 for detailed dietary studies and 2220 subjects participated in the present study (response rate : 84.5%). Participants with self-reported history of hypertension, diabetes or heart disease were excluded from the study (n=318) and thus the final study numbers were 1902 subjects. Dietary salt, energy, macronutrients and micronutrients intake were measured using a validated semi-quantitative food frequency questionnaire. Diagnosis of hypertension was based on the National Cholesterol Education Programme (NCEP) Adult Treatment Panel III criteria. Logistic regression analysis was used to look at the association of dietary salt with hypertension. Results : Mean dietary salt intake (8.5 g/d) in the population was higher than the recommended by the World Health Organization (<5g/d). Higher salt intake was associated with older age and higher income (p for trend<0.0001). Subjects in the highest quintile of salt intake had significantly higher prevalence of hypertension than did those in the lowest quintile (48.4 vs 16.6%, p<0.0001). Both systolic and diastolic blood pressure significantly increased with increase in quintiles of total dietary salt both among hypertensive and normotensive subjects (p for trend p1 teaspoon/day at the dining table was associated with a higher prevalence for hypertension compared to zero added salt (38.5% vs 23.3%, Chi-square = 18.95; p<0.0001). Multiple logistic regression analysis revealed that even after adjusting for age, gender, body mass index, total energy intake and dietary fat, total dietary salt intake was positively associated with hypertension. [Odds ratio (OR): 1.161, 95% Confidence Interval (CI): 1.115-1.209, p<0.0001]. Conclusion: Intake of dietary salt in urban south India is higher than currently recommended. Increasing salt intake is associated with increased risk for hypertension even after adjusting for potential confounders. This calls for urgent steps to decrease salt consumption of the population at high ris