Freestanding 3D Mesostructures,Functional Devices,and Shape‐Programmable Systems Based on Mechanically Induced Assembly with Shape Memory Polymers

Capabilities for controlled formation of sophisticated 3D micro/nanostructures in advanced materials have foundational implications across a broad range of fields. Recently developed methods use stress release in prestrained elastomeric substrates as a driving force for assembling 3D structures and functional microdevices from 2D precursors. A limitation of this approach is that releasing these structures from their substrate returns them to their original 2D layouts due to the elastic recovery of the constituent materials. Here, a concept in which shape memory polymers serve as a means to achieve freestanding 3D architectures from the same basic approach is introduced, with demonstrated ability to realize lateral dimensions, characteristic feature sizes, and thicknesses as small as ≈500, 10, and 5 µm simultaneously, and the potential to scale to much larger or smaller dimensions. Wireless electronic devices illustrate the capacity to integrate other materials and functional components into these 3D frameworks. Quantitative mechanics modeling and experimental measurements illustrate not only shape fixation but also capabilities that allow for structure recovery and shape programmability, as a form of 4D structural control. These ideas provide opportunities in fields ranging from micro‐electromechanical systems and microrobotics, to smart intravascular stents, tissue scaffolds, and many others.     

Method to Predict Tempering of Steels Under Non-isothermal Conditions

A common way of representing the tempering responses of steels is with a “tempering parameter” that includes the effect of temperature and time on hardness after hardening. Such functions, usually in graphical form, are available for many steels and have been applied for isothermal tempering. In this article, we demonstrate that the method can be extended to non-isothermal conditions. Controlled heating experiments were done on three grades in order to verify the method.     

A two failure modes system with cold stand-by units

This short paper presents a system with two mutually exclusive failure modes and N stand-by units. The repair is considered at one failure mode. The state probability equations are developed in Laplace transform.     

Reliability modeling of on-surface transit systems with human errors

This paper presents two newly developed Markov models representing on-surface transportation systems subject to hardware failures and human errors. Transit system reliability, steady state availability, mean time to failure (MTTF) and variance of time to failure formulas are developed. Selective plots are shown for each model.     

The state of reliability design specifications in Canadian industries: A survey

This paper presents the findings of a recent survey conducted on ‘reliability design specifications in Canadian manufacturing and service industries’. The survey is based upon a questionnaire mailed to various manufacturing and service industries in Canada. The questionnaire covered different aspects of organizational structure, reasons for emphasis on reliability and maintainability, areas of reliability engineering requiring improvement, most important parameters in equipment reliability specification, measures to improve system/equipment reliability, use of international or U.S. Military standards (reliability) in design specifications, reliability techniques and parameters specified when procuring an item, etc. The respondent organizations are classified into several groups, namely, Aerospace and defence, Electronics, Mechanical, Transportation, and others. General (all combined) and groupwise response analyses are performed.     

Bibliography of literature on telecommunication systems reliability

This paper presents an extensive list of selective references on telecommunication systems reliability.     

Effects of Weibull hazard rate on common cause failure analysis of reliability networks

This paper presents formulae for system mean life, variance of time to failure, hazard rate and reliability of parallel, k-out-of-n, parallel-series and bridge networks with common cause failures. The components in every configuration are assumed to be identical and characterized by a Weibull time to failure density function. The graphical plots of the system reliability and mean life gain are shown.     

User-Centric Learning and Evaluation of Interactive Segmentation Systems

Many successful applications of computer vision to image or video manipulation are interactive by nature. However, parameters of such systems are often trained neglecting the user. Traditionally, interactive systems have been treated in the same manner as their fully automatic counterparts. Their performance is evaluated by computing the accuracy of their solutions under some fixed set of user interactions. In this paper, we study the problem of evaluating and learning interactive segmentation systems which are extensively used in the real world. The key questions in this context are how to measure (1) the effort associated with a user interaction, and (2) the quality of the segmentation result as perceived by the user. We conduct a user study to analyze user behavior and answer these questions. Using the insights obtained from these experiments, we propose a framework to evaluate and learn interactive segmentation systems which brings the user in the loop. The framework is based on the use of an active robot user??a simulated model of a human user. We show how this approach can be used to evaluate and learn parameters of state-of-the-art interactive segmentation systems. We also show how simulated user models can be integrated into the popular max-margin method for parameter learning and propose an algorithm to solve the resulting optimisation problem.     

On the Dielectric Study of Se<Subscript>80−<Emphasis Type="Italic">x</Emphasis></Subscript>Te<Subscript>20</Subscript>Pb<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> (<Emphasis Type="Italic">x</Emphasis> = 0, 1 and 2) Glasses

In the present paper, the dielectric parameters such as the dielectric constant ε′(ω), dielectric loss ε″(ω) and alternating current (ac) conductivity have been investigated for bulk amorphous chalcogenide Se_80?x Te₂₀Pb _x (x = 0, 1 and 2) glasses in the frequency range 10 Hz to 500 kHz and within the temperature range from 300 K to 320 K. Dielectric constant ε′(ω) and dielectric loss ε″(ω) are found to be highly frequency (ω) and temperature dependent, and this behavior is interpreted on the basis of Guintini’s theory of dielectric dispersion. The ac conductivity (σ _ac) is found to be temperature independent and obey the power law ω ^s , where s < 1 and decreases as temperature rises. The obtained results are discussed in terms of the correlation barrier hopping model proposed by Elliot. The composition dependence of the dielectric constant, dielectric loss and ac conductivity are also discussed and reported here.