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.     

Performance of in-call buffer/window allocation schemes for short intermittent file transfers over broadband packet networks

While static open loop rate controls may be adequate for handling continuous bit rate (CBR) traffic, relatively smooth data traffic, and relatively low speed bursty data traffic over broadband integrated networks, high speed bursty data sources need more dynamic controls. Burst level resource allocation is one such dynamic control. Potential benefits and other issues for burst level resource parameter negotiations for bursty data traffic over high speed wide area packet networks have been discussed earlier.^1–6 A detailed analysis of an adaptive buffer/window negotiation scheme for long file transfers using these concepts is presented in Reference 1. In this paper we discuss two burst level buffer/window negotiation schemes for short intermittent file transfers, focusing on the specific needs of such traffic streams. We develop closed network of queues models to reflect the behaviour of the proposed schemes. These models, while being simple, capture essential details of the control schemes. Under fairly general assumptions, the resulting network of queues is of product form and can be analysed using the mean value analysis. We use such an analysis to compare the proposed schemes and to determine appropriate sizes of trunk buffers to achieve the desired balance between bandwidth utilization and file transfer delay. The effects of other parameters on the performance of these schemes as well as on the buffer sizing rules are also discussed. Burst level (in-call) parameter negotiation may be carried out by the end system with the network elements or by an interface system (access controller) with the broadband network elements. We discuss implications of this location as well as the needed protocol features. Finally, the service discrimination capabilities desired at the trunk controllers in switching nodes are briefly discussed.     

$$E^{2} SR^{2}$$ E 2 S R 2 : An acknowledgement-based mobile sink routing protocol with rechargeable sensors for wireless sensor networks

Wireless Networks - The advances in hardware manufacturing technologies and wireless communications enabled the evolution of tiny, multi-functional, low-power and resource constrained sensor nodes...     

Influence of Abrasive Properties on Residual Stresses in Lapped Ferrite and Alumina

The effect of abrasive-particle properties on surface-finishing residual stresses, surface finish, and material removal rates during the lapping of ferrite and aluminium oxide is quantified experimentally. It is shown that lapping with softer abrasives and smaller particles results in lower compressive residual stresses near the surface and improved surface finish. These results demonstrate possible methods for controlling surface finishing residual stresses in ceramics while at the same time achieving dimensional accuracy.     

Effect of alkali on filaments of poly(ethylene terephthalate) and its copolyesters. II. Presence of quaternary ammonium salt in the alkali-bath

Influence of alkyl (C₁₂–C₁₄)-dimethyl-benzyl ammonium chloride in the solution of sodium hydroxide on the hydrolysis of poly(ethylene terephthalate) (PET), anionically modified poly(ethylene terephthalate) copolyster (CDP), and block polymer of poly(ethylene terephthalate)-poly(ethylene glycol) (EDP), has been studied under a variety of proportions, concentrations, time and temperature of reaction, M : L ratio, etc. Mechanical properties of treated polymeric materials are evaluated. Hydrolysis of two polymers in the same bath is compared with that in separate baths.     

Unification of Blockchain and Internet of Things (BIoT): requirements,working model,challenges and future directions

Wireless Networks - The Internet of Things (IoTs) enables coupling of digital and physical objects using worthy communication technologies and introduces a future vision where computing systems,...     

Electricity prices and state commitment to energy efficiency in the U.S.

This paper studies the effect of electricity prices on state commitment to energy efficiency in the USA. Using panel data we find that electricity prices have a significant positive effect on state energy efficiency expenditures. Moreover, we find that this effect is particularly pronounced beyond a certain threshold level of prices. The rationale for these findings is that higher prices increase the cost-effectiveness of energy efficiency programs. These findings have important implications for state expenditures on energy efficiency if electricity prices rise in response to carbon and other stringent environmental regulations.     

Starch Hydrolysate,an Optimal and Economical Source of Carbon for the Secretion of Citric Acid by Yarrowia lipolytica (DS-1)

Using Yarrowia lipolytica (DS-1), secretion of citric acid is studied as a function of carbon sources such as glucose, fructose, hydrol, sucrose, cane sugar molasses, kerosene (all available commercially) and tapioca starch hydrolysate, invert sucrose and invert cane sugar molasses (all prepared in laboratory). On the basis of their acceptability by DS-1 for citric and isocitric acid secretion, it is concluded that (a) sucrose and cane sugar molasses (with/without inversion) served as poor carbon sources, (b) fructose, hydrol, impure tapioca starch hydrolysate (96 DE w/w) and invert sucrose served as relatively better carbon sources and (c) purified tapioca starch hydrolysate (96 DE w/w) was the best carbon source to substitute glucose by giving comparable (75%) efficiency of conversion and economical advantage.     

Influences of Mesoporosity Generation in ZSM-5 and Zeolite Beta on Catalytic Performance During <Emphasis Type=Italic>n</Emphasis>-Hexane Isomerization

Abstract  

Catalytic performance of Pt impregnated parent and desilicated nano-crystalline zeolites, ZSM-5 and Beta for n-hexane isomerization was studied. Difference in channel systems of the zeolites and absence/presence of mesopores therein were found to be reflected in product distributions. ZSM-5 was desilicated by NaOH and zeolite Beta with tetramethylammonium hydroxide (TMAOH.) Desilication was found to afford comparable catalytic performance to that of the parent counterpart at reaction temperature lower by 25 °C. Observed product distributions could be substantiated with characterizations such as ammonia TPD, surface area determination and SEM. Desilicated zeolite Beta was seen to be less prone to coking as deduced from the TGA study. Location of Pt with reference to proton sites within the channels and that inside the pores viz a viz external surface also have been discussed briefly.     

Surface,tribological, and mechanical characterization of synthetic skins for tribological applications in cosmetic science

Synthetic skin as an ideal human‐tissue substitute is needed for the research and assessment of hair‐ and skin‐care products. In this study, a systematic study was carried out of the surface, tribological, and mechanical properties of two synthetic skins and rat skin with and without skin‐cream treatment with scanning electron microscopy, atomic force microscopy, and a nanoindenter. The film thickness, adhesive force, coefficient of friction, surface roughness, and contact angle of the two synthetic skins and rat skin were comparable. The hardness of one synthetic skin was more similar to rat skin. After treatment with skin cream, the trends of the properties of the two synthetic skins and rat skin were similar. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011