On selection of forwarding nodes for long opportunistic routes

Opportunistic routing is a promising routing paradigm which increases the network throughput. It forces the sender’s neighbors, who successfully overheard the transmitted packet, to participate in the packet forwarding process as intermediate forwarding nodes. As a seminal opportunistic routing protocol, MORE combines network coding idea with opportunistic routing to eliminate the need for strict coordination among active forwarding nodes. In this paper, we show that MORE performance does not scale well with the route length, especially when the route length goes beyond two hops. Also, we found that MORE fails to establish a working opportunistic route in sparse networks. Clearly, the network throughput is directly influenced by both the quantity and quality of forwarding nodes, and their cooperation order. In this paper, we propose a new forwarder selection mechanism which considers the route length, link qualities, the distance from the source, and nodes density. It eliminates the occasional route disconnectivity happening in MORE and improves the quality of the established opportunistic routes. The simulation result indicates that our proposal always outperforms MORE when dealing with long opportunistic routes.

     

Prediction of Particle Deposition Using a Simplified Particle Model in Fully Developed Channel Flow

In this study the Eulerian particle model was modified to predict the particle deposition rate in fully developed channel flow. The modified model is less complicated and has much lower computation time. The performance of the simplified model was examined by comparing the particle deposition rate in a vertical channel with the experimental data for fully developed channel flow available in the literature. The effects of turbophoretic force, thermophoretic force, electrostatic force, gravitational force, Brownian/turbulent diffusion, and the wall roughness on the particle deposition rate were examined. The predictions of the modified particle model were in agreement with the experimental data.     

Utilization of textile wastewater as carbon source by newly isolated <Emphasis Type="Italic">Haloarcula</Emphasis> sp<Emphasis Type="Italic">.</Emphasis> IRU1: optimization of conditions by Taguchi methodology

Wastewater of textile industry is one of the most important threats to the environment and human health. The Taguchi methodology was applied to optimize conditions for the growth of a novel Haloarcula sp. IRU1 with a textile wastewater as carbon source by evaluating the influence of temperature, concentration of textile wastewater and pH on biomass of Haloarcula sp. IRU1. We intended to evaluate biodegradation ability of this bacterium. Highest biomass of Haloarcula sp. IRU1 was achieved at temperature 47°C, concentration of textile wastewater 7% v/v and pH 9. In conclusion, the isolated halophilic bacterium Haloarcula sp. IRU1 can utilize textile wastewater as carbon source and biodegrade it in different conditions.     

Challenges and trends in the allocation of the workforce in manufacturing shop floors

This paper presents a critical and focused review of definitions, challenges and developments of the workforce allocation system in manufacturing shop floors with a particular emphasis on response to changes and disturbances. The continuously changing requirements in production environments have been the driving force behind several stages of evolution experienced by management of workforce allocation. The paper includes an in-depth examination of the phenomena of changes and disturbances in the production shop floor. This is followed by an assessment of the readiness of workforce allocation systems to respond to such events with respect to both workforce perception and system architecture. Recent developments of the workforce allocation models suggest that the use of intelligent and distributed systems and techniques offer solutions that are responsive, flexible, and multi-criteria. To this end, an overview of a recent study in the application of the principles of holonic manufacturing systems, as an example of intelligent system approach to develop a flexible workforce allocation model, is presented.     

Hemodialysis cost in Tehran,Iran

The purpose of this study was to assess the health service cost of hemodialysis (HD) delivered at hospitals in Iran as a developing country with a well‐defined program of renal replacement therapy. A cost analysis was performed from the viewpoint of the 2 hospitals, with 3 shifts and full chairs, on current practice for dialysis maintenance. Cost and patient data were collected in 2006 and from April 1 to May 31, 2007, respectively. A total of 22,464 HD sessions were performed and 247 patients were studied during the study period. The reference year for the value of USD for different mentioned costs was 2006. Health care sector costs associated with each HD session were estimated at US$78.87. Most of the total maintenance expenditure was made up of medical supplies (36.19%), with dialyzers as the major cost driver. Staff salaries represented 17% of the cost and fixed direct capital costs accounted for 21.4%. Of the family members, 32.4% accompanied their patients. The mean cost for transportation of patients and accompanied person was US$3.15 ± 2.83 and US$1.5 ± 0.29, respectively. These findings are important in the light of limited available resources coupled with the increasing prevalence of kidney failure. A major attempt should also be made to increase peritoneal dialysis coverage as in some centers we cannot keep all chairs full, especially in some vast areas. It is highly recommended to place initial focus on strategies and treatments that slow disease progression, to postpone renal replacement therapy to save resources.     

Automated robotic grinding by low-powered manipulator

A new robotic grinding process has been developed for a low-powered robot system using a spring balancer as a suspension system. To manipulate a robot-arm in the vertical plane, a large actuator torque is required due to the tool weight and enormous gravity effect. But the actuators of the robot system always exhibit a limited torque capacity. This paper presents a cheap and available system for precise grinding tasks by a low-powered robot system using a suspension system. For grinding operations, to achieve position and force-tracking simultaneously, this paper presents an algorithm of the hybrid position/force-tracking scheme with respect to the dynamic behavior of a spring balancer. Material Removal Rate (MRR) is developed for materials SS400 and SUS304. Simulations and experiments have been carried out to demonstrate the feasibility of the proposed system.     

Management of sustainable manufacturing systems-a review on mathematical problems

The ever-growing awareness of environmental protection has significantly influenced the method of manufacturing products. Due to the introduction of new processes, the management of sustainable manufacturing shows different characteristics to those of traditional systems. Sustainable manufacturing systems have attracted a great deal of attention in the past 20 years as an emerging manufacturing approach. Particularly in the last 10 years, the number of papers focusing on the topic of sustainable manufacturing systems’ management has increased rapidly. More and more practical factors have been considered and integrated into this area which makes it more complex, but closer to reality. This paper aims to classify the mathematical problems dealing with the management of sustainable manufacturing systems. More than 100 related papers mainly from 1994 to 2015 have been selected and reviewed and divided into three categories according to the main elements in a manufacturing system: production planning and control, inventory management and control and manufacturing network design. The development of each category is summarised and the corresponding mathematical problems are discussed to provide a general overview of the relevant research fields and identify future research directions.     

Performance analysis of the internet‐protocol multimedia‐subsystem's control layer using a detailed queueing Petri‐net model

In the current trend in telecommunications industry towards all‐internet‐protocol (IP) infrastructures, IP multimedia subsystem (IMS) plays a critical role by providing a coherent data and control‐plane solution for large‐scale live multimedia applications in a flexible and cost‐effective manner. On the other hand, such a large‐scale service platform would inevitably fail without effective support for the quality‐of‐service (QoS) requirements perceived by its users. Among the most important factors that influence user QoS are system performance and scalability. In this paper, a performance model for IMS systems is developed using the queueing Petri nets (QPNs) as the modeling formalism. The model's parameters are tuned based on the measurements carried out using a well‐known IMS implementation. The model is validated against the real system. During the model calibration, the Java garbage‐collector process used in the home subscriber‐server (HSS) implementation was found to be a main factor in the discrepancy between the model and the reality. In addition, the effects of other factors such as the network stack in the operating system are investigated. The validated model is employed to give insights into the scalability of every single instance of IMS implementation. The model is extended to study load balancing among multiple instances of HSS to remove the main bottleneck in the system. It provides a valuable platform for resource management of various components of the IMS ecosystem to support the intended level of QoS for the users.     

Application of a flexible structure artificial neural network on a servo-hydraulic rotary actuator

In this article the results of the application of a flexible structure artificial neural network for controlling the angular velocity of a servo-hydraulic rotary actuator are discussed. A mathematical model for the system is derived, and a flexible artificial neural network (ANN)-based controller with the feedback error learning method as a learning algorithm is applied to the system. The neural network-based controller has a feed-forward structure and three layers. The flexible bipolar sigmoid function was used as the activation function of the network. The simulation and experimental results show good performance of the developed method in learning the inverse dynamic of the system and controlling the angular velocity of the rotary hydro motor. The advantages of the developed method for servo-hydraulic actuators over other traditional approaches are discussed.     

Investigation of asphaltene deposition under dynamic flow conditions

Asphaltene deposition is one of the most serious problems, which usually occurs in oil wells, petroleum production, oil processing, and transportation facilities. Deposition of heavy organic components, especially asphaltene, can lead to wellbore blockage and impacts well economics due to reduction in oil production. Therefore, it is necessary to pay more attention to finding some solution to overcome this problem. In this study, a pipe-loop apparatus for investigation of oil stability was employed to measure deposition thickness using a thermal method. The effects of many factors such as oil type, oil temperature, oil velocity, inhibitors, and solvents on asphaltene deposition were investigated. The results showed that the deposition increased with the increasing value of the colloidal instability index. Besides, the deposition thickness increased with the decreasing velocity of oil, but did not change with oil temperature. In addition, n-heptane could result in more deposition; however, toluene had no effect on the deposition. Branched dodecyl benzene sulfonic acid (Branched DBSA) and Linear DBSA as inhibitors decreased the rate of asphaltene deposition.