Predictive analytical modeling of cutting forces generated by high-speed machining of ductile and hard metals

This paper proposes an analytical cutting forces model based on an extension of the Oxley's machining theory (OMT) to high-speed machining of ductile and hard metals. In this model, the materials' behavior was modeled using the Marusich's constitutive equation (MCE). Furthermore, The OMT was modified to be able to capture the effects of the cutting tool edge radius and the burnishing phenomenon by implementing a variable rake angle equation and the Briks criterion, respectively. The predictive model was validated using experimental data obtained during the orthogonal machining of two aluminum alloys (AA6061-T6 and AA7075-T651) and induction-hardened AISI4340 steel (58-60 HRC). The results showed that the predicted and experimental cutting forces were in reasonable agreement for all tested materials. The strain rate constant in the primary shear zone (C₀) was found to be significantly sensitive to the cutting conditions and work material, and its effect on the predicted data was highlighted and discussed in depth. On one hand, it was found that AA6061-T6 is less sensitive to the strain rate compared to the AA7075-T651. On the other hand, all tested materials were found to be more sensitive to the strain rate at low cutting speeds and/or cutting feeds.     

Optimal business process deployment cost in cloud resources

Cloud computing is the fastest emerging technology that proposes several resources under various pricing strategies that are specified based on temporal constraints. The main aim of cloud computing is to enhance the performance level and minimize operating costs. Thus, organizations looking towards optimizing their spending on IT infrastructure find such pricing strategies very attractive, especially, to deploy their business process models. However, discovering the optimal deployment cost of a business process in cloud resources proposed under various pricing strategies becomes a highly challenging problem. So, the objective of the present paper is to present an approach that assists business process designers in finding an optimal assignment or scheduling based on the variety of pricing strategies. We use linear programming models with an objective function under a set of constraints. Besides, we propose an extension of the famous cloud simulator provided in the market, CloudSim, to simulate the cloud resources consumed to deploy a business process model. The experimental results show the feasibility, effectiveness, and performance of our approach.

     

Regioregular poly(3‐alkylthiophenes): Synthesis,characterization, and application in conductive fabrics

Poly(3‐dodecylthiophene) (P3DDT) and poly(3‐decylthiophene) (P3DT) with high contents of head‐to‐tail linkages (86 and 85%, respectively) were synthesized in high yields by a facile oxidative polymerization with ferric chloride in chloroform at room temperature. We believe that the low concentration and ultraslow addition of monomers to ferric chloride contributed to the high regioregularity. Differential scanning calorimetry thermograms indicated that the formed polymers consisted of crystalline, quasiordered, and disordered phases, which is a common feature of highly regioregular polymers. We prepared conductive fabrics with specific resistance of 30 and 100 Ω/sq by impregnating polyamide fabrics in a chloroform solution of P3DDT and P3DT, respectively. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2131–2135, 2004     

Continuous aggregate nearest neighbor queries

This paper addresses the problem of continuous aggregate nearest-neighbor (CANN) queries for moving objects in spatio-temporal data stream management systems. A CANN query specifies a set of landmarks, an integer k, and an aggregate distance function f (e.g., min, max, or sum), where f computes the aggregate distance between a moving object and each of the landmarks. The answer to this continuous query is the set of k moving objects that have the smallest aggregate distance f. A CANN query may also be viewed as a combined set of nearest neighbor queries. We introduce several algorithms to continuously and incrementally answer CANN queries. Extensive experimentation shows that the proposed operators outperform the state-of-the-art algorithms by up to a factor of 3 and incur low memory overhead.     

Design and evaluation of a device worn for fall detection and localization: Application for the continuous monitoring of risks incurred by dependents in an Alzheimer’s care unit

The Homecare project, which is part of a research project funded by the French National Research Agency (ANR), aims to define a new multi-sensor monitoring system for the elderly with cognitive disabilities in a care unit. Two subjects were recruited to participate to experimental trials. The main objective of this project is to design and test a complete monitoring system at a real site. It is a new clinical and technical approach which is complex to implement: Homecare is intended to propose a possible technical solution, demonstrate its feasibility and illustrate its use working at a protected site. The system consists of a motion sensor network deployed on the ceiling to monitor motion and an electronic patch worn by the subjects to identify them and detect falls. In order to locate tagged subjects inside the care unit, a network of anchor points is used. From these positions and movement data, an analysis algorithm detects an abnormal situation and alerts the nursing staff in real time. A Web application allows the medical staff to access movements and alarms. The complete monitoring system has been functioning for several months and continuously monitors two patients around the clock. In this paper, we present the implementation of the system, the method of localization inside the care unit, and the characterization of the fall detector, and we show certain results relating to activity data.     

Similarity queries: their conceptual evaluation, transformations, and processing

Many application scenarios can significantly benefit from the identification and processing of similarities in the data. Even though some work has been done to extend the semantics of some operators, for example join and selection, to be aware of data similarities, there has not been much study on the role and implementation of similarity-aware operations as first-class database operators. Furthermore, very little work has addressed the problem of evaluating and optimizing queries that combine several similarity operations. The focus of this paper is the study of similarity queries that contain one or multiple first-class similarity database operators such as Similarity Selection, Similarity Join, and Similarity Group-by. Particularly, we analyze the implementation techniques of several similarity operators, introduce a consistent and comprehensive conceptual evaluation model for similarity queries, and present a rich set of transformation rules to extend cost-based query optimization to the case of similarity queries.     

Investigation of the thermal degradation of polyurea: The effect of ammonium polyphosphate and expandable graphite

Polyurea was compounded with ammonium polyphosphate and expandable graphite and the morphology was studied by atomic force microscopy. The thermal degradation of polyurea and polyurea compounded with the additives has been investigated using thermogravimetry coupled with Fourier Transform infrared spectroscopy and mass spectrometry. The study of the thermal degradation and the parameters affecting the thermal stability of PU is essential in order to effectively design flame retarded polyurea. In general, thermal decomposition of polyurea occurs in two steps assigned to the degradation of the hard segment and soft segment, respectively. Adding these additives accelerates the decomposition reaction of polyurea. However, it is clear that more char is formed. This char is thermally more stable than the carbonaceous structure obtained from neat PU. The intumescent shield traps the polymer fragments and limits the evolution of small flammable molecules that are able to feed the flame.     

A household’s power load response to a change in the electricity pricing scheme: An expanded microeconomic-physical approach

Energy economists are interested in how changes in electricity prices prompt a response in end-user electricity demand. If historical prices are low or seldom change, it becomes difficult to estimate price elasticities statistically, especially in the short-run. Thus, a framework that merges the physical equations that govern how electricity is consumed, and a utility-maximizing household the responds to varying expenditures on electricity, is used.We have parameterized the physical component to a house in Saudi Arabia. Three electricity pricing schemes are analyzed: progressive tariffs, time-of-use prices, and real-time prices. We show that for a household with a low preference for electricity, slight price increases do warrant adjustment in indoor temperature in the hot summer months and lower consumer electronics use. Since we adopt a dwelling in Saudi Arabia, the response measure that is most exercised is the thermostat set-point adjustment. A subdued response is found for households that have adopted higher energy efficiency, or have high preference for electricity.     

Routing in Wireless Sensor Networks Using Optimization Techniques: A Survey

Wireless Personal Communications - Over the past few decades, one of the important advancements in wireless communication is low cost and limited power devices known as wireless sensor networks...