On the reliability of electrostatic NEMS/MEMS devices: Review of present knowledge on the dielectric charging and stiction failure mechanisms and novel characterization methodologies

This paper reviews the state of the art knowledge related to critical failure mechanisms in electrostatic micro- and nano-electromechanical systems (MEMS and NEMS) which are the dielectric charging and stiction. It describes also the recent employed nanoscale characterization techniques for these phenomena based on Kelvin probe force microscopy (KPFM) and force–distance curve measurements. The influence of relative humidity and dielectric deposition conditions on the charging/discharging processes is discussed. Moreover, different stiction mechanisms induced by electrostatic force and/or meniscus formation are analyzed. Finally, novel characterization methods are presented and used to correlate between the results from MEMS devices and metal–insulator–metal (MIM) capacitors. These methods are employed in view of application in electrostatic capacitive MEMS switches and could be easily extended to explore other NEMS/MEMS devices. The study provides an accurate understanding of the charging and stiction related failure mechanisms, presents guidelines for a proper packaging environment, and reveals precise explanations for the literature reported device level measurements of electrostatic MEMS devices.     

Simplified dynamic analysis of eccentric buildings with a setback. 2: the effect of stiffness irregularity

The effect of stiffness irregularity is investigated in eccentric buildings with a setback. Stiffness irregularity is assumed to be created when some of the lateral load resisting bents are curtailed at the top of the base structure. The methodology suggested in the companion paper for assessing vibration frequencies, base shears and torques is extended to include the effect of curtailed bents. Their contribution is evaluated by an indirect method after the modal stiffness of the symmetrical counterpart structure is determined and the modal contribution of the full height bents is assessed by Southwell's approach. A number of numerical examples, representing common types of building structures, are presented to illustrate the procedure and provide an insight into the response of such setback buildings. The results are compared with more accurate results obtained by three‐dimensional dynamic analyses. Copyright © 2009 John Wiley & Sons, Ltd.     

Review of Life-Cycle Assessment Applications in Building Construction

Life-cycle assessment (LCA) has been used to assess product development processes “from cradle to grave” for many years. With the current push toward sustainable construction, LCA has gained importance as an objective method to evaluate the environmental impact of construction practices. A substantial amount of construction-related LCA work has been published recently; however, most of this work has been fragmented and a systematic compilation of this literature has not been undertaken. This article presents a structured review of building construction-related LCA literature, classified under four categories: LCA applications for construction products selection; LCA applications for construction systems/process evaluation; LCA tools and databases related to the construction industry; and LCA methodological developments related to the construction industry. Current challenges for using LCA in construction are discussed and potential areas for future research are highlighted. This review and similar efforts may provide the construction industry and associated researchers the necessary background to make better-informed construction decisions and assist the development of an agenda for further research.     

Microwave dielectric properties of novel temperature stable high Q Li2Mg1−xZnxTi3O8 and Li2A1−xCaxTi3O8 (A = Mg,Zn) ceramics

The Li₂Mg_1?xZn_xTi₃O₈ (x = 0–1) and Li₂A_1?xCa_xTi₃O₈ (A = Mg, Zn and x = 0–0.2) ceramics are synthesized by solid-state ceramic route and the microwave dielectric properties are investigated. The Li₂MgTi₃O₈ ceramic shows ?_r = 27.2, Q_u × f = 42,000 GHz, and τ_f = (+)3.2 ppm/°C and Li₂ZnTi₃O₈ has ?_r = 25.6, Q_u × f = 72,000 GHz, and τ_f = (?)11.2 ppm/°C respectively when sintered at 1075 °C/4 h. The Li₂Mg_0.9Zn_0.1Ti₃O₈ dielectric ceramic composition shows the best dielectric properties with ?_r = 27, Q_u × f = 62,000 GHz, and τ_f = (+)1.1 ppm/°C. The effect of Ca substitution on the structure, microstructure and microwave dielectric properties of Li₂A_1?xCa_xTi₃O₈ (A = Mg, Zn and x = 0–0.2) has also been investigated. The materials reported in this paper are excellent in terms of dielectric properties and cost of production compared to commercially available high Q dielectric resonators.     

What Rule(s) Should I Use?

Rules in schemas apply to shapes in terms of embedding. This melds calculating with art and design, and has many uses in teaching and in practice.     

A bicriteria approach to minimize the total weighted number of tardy jobs with convex controllable processing times and assignable due dates

We study a single-machine scheduling problem in a flexible framework where both job processing times and due dates are decision variables to be determined by the scheduler. The model can also be applied for quoting delivery times when some parts of the jobs may be outsourced. We analyze the problem for two due date assignment methods and a convex resource consumption function. For each due date assignment method, we provide a bicriteria analysis where the first criterion is to minimize the total weighted number of tardy jobs plus due date assignment cost, and the second criterion is to minimize total weighted resource consumption. We consider four different models for treating the two criteria. Although the problem of minimizing a single integrated objective function can be solved in polynomial time, we prove that the three bicriteria models are NP\mathcal{NP}-hard for both due date assignment methods. We also present special cases, which frequently occur in practice, and in which all four models are polynomially solvable.     

Multifunctional materials: engineering applications and processing challenges

Multifunctional materials are designed so as to meet specific requirements through tailored properties. Smart materials can be considered as multifunctional ones that have the ability to react upon an external stimulus, simulating, in this way, the behavior of nature’s materials. Furthermore, the introduction of biomemetics in the material science, allows the designing of materials with similar processes as nature does: building from molecules to complete structures. This paper focuses on the presentation of the various multifunctional materials reported in the literature and the processing means developed.     

Water absorbance and thermal properties of sulfated wheat gluten films

Wheat gluten films of various thicknesses formed at 30–70°C were treated with cold sulfuric acid to produce sulfated gluten films. Chemical, thermal, thermal stability, and water uptake properties were characterized for neat and sulfated films. The sulfated gluten films were able to absorb up to 30 times their weight in deionized water. However, this value dropped to 3.5 when the film was soaked in a 0.9% (w/w) NaCl solution. The films were also soaked 4 times in deionized water, and each soaking resulted in a reduced water uptake capacity. The temperature of film formation had no effect on the final water uptake properties. Also, thinner films had higher concentrations of sulfate groups than thicker films; this resulted in higher water uptake values. In addition, sulfated gluten films had comparable glass‐transition temperatures but lower thermal stabilities than the neat gluten films. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Health claims: Consumers’ matters

This paper presents a systematic literature review of studies investigating the extent and the ways in which health claims influence consumers. It focuses on published international research on health claims from US, Australia, Canada, Brazil and European countries. Research papers (n = 42) that were identified were coded in terms of sample type, research objectives/questions, research design and methodological details, as well as results and implications for future research. Results provide a systematic overview of the context in which health claims have been examined in the past and present a synthesis of findings in six thematic categories, namely knowledge/awareness of dietary issues, effects of health claims on purchase decisions, effects of health claims on perception/attitudes/beliefs, sources of information and trust, framing of health claims and disease-risk reduction and health-enhancing claims as well as consumer purchase decision.