Economic‐Statistical Design of Acceptance Control Chart

Acceptance control charts are effective tools to monitor capable processes in which the fraction of the produced nonconforming items is very low. In these charts, some controlled changes in the process mean are allowed, and the production of a specified number of defectives is tolerated. Designing these acceptance control charts by considering the cost of sampling, detecting, and investigating out‐of‐control signals as well as the probable correction of assignable cause(s) can result in economic advantages. Moreover, the statistical properties of the control charts can be satisfied. In this article, an economic‐statistical model is developed to design acceptance control charts. An illustrative example is used to compare the results of economic versus economic‐statistical design of the acceptance control charts. In addition, a comprehensive sensitivity analysis is conducted on the basis of the parameters of the model. Copyright © 2012 John Wiley & Sons, Ltd.     

Phase II monitoring of multivariate multiple linear regression profiles

In certain cases, the quality of a process or a product can be effectively characterized by two or more multiple linear regression profiles in which response variables are correlated. This structure can be modeled as multivariate multiple linear regression profiles. When linear profiles are monitored separately, then correlation between response variables is ignored and misleading results could be expected. To overcome this problem, the use of methods that consider the multivariate structure between response variables is inevitable. In this paper, we propose four methods to monitor this structure in Phase II. The performance of the methods is compared through simulation studies in terms of the average run length criterion. Furthermore, a method based on likelihood ratio approach is developed to determine the location of shifts and a numerical simulation is used to evaluate the performance of the proposed method. Finally, the use of the methods is illustrated by a numerical example. Copyright © 2010 John Wiley & Sons, Ltd.     

Using orthogonal pairs of rollers on concave beds (OPRCB) as a base isolation system—part I: analytical,experimental and numerical studies of OPRCB isolators

A somehow new isolating system is introduced for short‐ to mid‐rise buildings. It does not need high technology for manufacturing and is not costly, contrary to other existing systems like lead‐rubber bearing or friction pendulum bearing systems. Each isolator of the proposed system consists of two Orthogonal Pairs of Rollers on Concave Beds (OPRCB). Rolling rods installed in two orthogonal directions make possible the movement of the superstructure in all horizontal directions. The concave beds, in addition to giving the system both restoring and re‐centring capabilities, make the force–displacement behaviour of the isolators to be of hardening type. The results of the studies on the specifications of the proposed isolating system and its application to buildings can be presented in two parts. Part I relates to the analytical formulations and the results of experimental and numerical studies of the system's mechanical feature, including its dynamical properties, and part II focuses on the effectiveness of the proposed isolation system in seismic response reduction of low‐ to mid‐rise buildings. In part I of the work, presented in this paper, at first general features of the OPRCB isolator are explained and the analytical formulation, governing its dynamic motion, is derived and discussed in detail. Then, the results of experimental and numerical investigations, including the lateral load displacement relationship of the OPRCB isolators under various vertical loads, obtained by both Finite Element Analyses (FEA) and laboratory tests are presented (FEA results have been verified by the laboratory tests). Finally, responses of some Single Degree of Freedom (SDOF) systems, isolated by OPRCB devices, subjected to simultaneous effect of horizontal and vertical ground motions, are presented and compared with responses of their fixed‐base counterparts. Based on the numerical calculations, it is observed that the oscillation period of the isolated SDOF system is independent of its mass, the initial amplitude of its free vibration response and the value of rolling resistance coefficient. With regard to seismic response reduction it is seen that the amount of absolute accelerations in the SDOF systems, isolated by OPRCB devices, can be reduced drastically in comparison with the fixed‐base systems. Results also show that if the rollers and cylindrical beds are made of high‐strength steel materials, the system can be used effectively under the vertical loads of about the axial forces of ground floor columns in ordinary buildings up to 14 storeys. Copyright © 2010 John Wiley & Sons, Ltd.     

Monitoring a labeled degree-corrected stochastic block model

The stochastic block model (SBM) is a random graph model that focuses on partitioning the nodes into blocks or communities. A degree-corrected stochastic block model (DCSBM) considers degree heterogeneity within nodes. Investigation of the type of edge label can be useful for studying networks. We have proposed a labeled degree-corrected stochastic block model (LDCSBM), added the probability of the occurrence of each edge label, and monitored the behavior of this network. The LDCSBM is a dynamic network that varies over time; thus, we applied the monitoring process to both the US Senate voting network and simulated networks by defining structural changes. We used the Shewhart control chart for detecting changes and studied the effect of Phase I parameter estimation on Phase II performance. The efficiency of the model for surveillance has been evaluated using the average run length for estimated parameters.     

Electro-Elastic Wetting: A Method to Migrate and Deform Droplets

A new wetting mechanism, termed electro-elastic wetting, and methods to exploit it for droplet manipulation are proposed and demonstrated. The system consists of a droplet of dielectric liquid, an elastic and conductive membrane as its shell, and an electrode-dielectric composite as its substrate. Activation is by an electric field applied between the membrane and the substrate. The equilibrium shape of the droplet is determined by the balance of membrane tension and electrostatic attraction. It is shown that the contact angle of the droplet is governed by a modified Young–Lipmann Equation. It is then demonstrated that it is possible to transport the droplet along a controlled direction, as well as to actively tune its shape, topography, and position by manipulating the spatial distribution of the electrical force.     

Polyampholyte Polymers-Based Sensors: A Review on Stimuli and Applications

Polyampholytes are a specific type of zwitterionic materials composed of monomers with both positive and negative charges. These materials can be synthesized through various methods, such as free radical, anionic, or cationic polymerization, or by modifying existing polymers through postpolymerization processes. Polyampholytes possess unique properties that make them attractive for a wide range of applications, particularly in sensor technology. They can undergo conformational changes in response to external stimuli like pH variations, temperature fluctuations, or changes in salt concentration. These properties have led to their application in biosensors, salt and ion sensors, pH sensors, fluorescence-based sensors, strain sensors, and thermosensitive sensors. It is worth noting that in some cases polyampholytes can respond to multiple stimuli simultaneously. Overall, polyampholytes are drawing great attention for their excellent mechanical properties including self-healing, high toughness, and fatigue resistance. Thus, this review is focused on advances that are made to develop polyampholyte polymer-based sensors in different applications.