Simulation of Perfluoropolyether Lubricant Films

2002 ◽  
Author(s):  
M. S. Jhon ◽  
S. Izumisawa ◽  
Q. Guo ◽  
Y. T. Hsia
Keyword(s):  
Data Storage ◽  
Disk Drive ◽  
Chain Structure ◽  
Solid Surfaces ◽  
Random Copolymers ◽  
Hydroxyl Groups ◽  
Polar Interactions ◽  
And Performance ◽  
Drive Systems ◽  
Pfpe Lubricants

Thin-film lubricants play a key role in high-density data storage capabilities via increased reliability and performance of hard disk drive systems. The commercially-used perfluoropolyether (PFPE) lubricants are random copolymers with a linear, polymeric backbone chain structure: X–[(OCF2CF2)p–(OCF2)q]–O–X (p/q ≅ 2/3). Here, X (representing the endgroups) is CF3 in PFPE Z (non-reactive) and CF2CH2OH in PFPE Zdol (reactive), where the hydroxyl groups in PFPE Zdol exhibits strong polar interactions with solid surfaces and with other endgroups. Figure 1 illustrates the representative bead-spring models [1,2] for PFPE Zdol examined in this paper.

scholarly journals Performance Evaluations of Distributed File Systems for Scientific Big Data in FUSE Environment

Electronics ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 1471
Author(s):  
Jun-Yeong Lee ◽  
Moon-Hyun Kim ◽  
Syed Asif Raza Raza Shah ◽  
Sang-Un Ahn ◽  
Heejun Yoon ◽  
...  
Keyword(s):  
Data Storage ◽  
Scale Up ◽  
File Systems ◽  
Performance Evaluations ◽  
Distributed File Systems ◽  
Data Intensive Computing ◽  
Data Intensive ◽  
Tremendous Amount ◽  
Computing Environments ◽  
And Performance

Data are important and ever growing in data-intensive scientific environments. Such research data growth requires data storage systems that play pivotal roles in data management and analysis for scientific discoveries. Redundant Array of Independent Disks (RAID), a well-known storage technology combining multiple disks into a single large logical volume, has been widely used for the purpose of data redundancy and performance improvement. However, this requires RAID-capable hardware or software to build up a RAID-enabled disk array. In addition, it is difficult to scale up the RAID-based storage. In order to mitigate such a problem, many distributed file systems have been developed and are being actively used in various environments, especially in data-intensive computing facilities, where a tremendous amount of data have to be handled. In this study, we investigated and benchmarked various distributed file systems, such as Ceph, GlusterFS, Lustre and EOS for data-intensive environments. In our experiment, we configured the distributed file systems under a Reliable Array of Independent Nodes (RAIN) structure and a Filesystem in Userspace (FUSE) environment. Our results identify the characteristics of each file system that affect the read and write performance depending on the features of data, which have to be considered in data-intensive computing environments.

scholarly journals Multiblock Copolymers of Norbornene and Cyclododecene: Chain Structure and Properties

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1756
Author(s):  
Yulia I. Denisova ◽  
Georgiy A. Shandryuk ◽  
Marianna P. Arinina ◽  
Ivan S. Levin ◽  
Vsevolod A. Zhigarev ◽  
...  
Keyword(s):  
First Generation ◽  
Average Length ◽  
Chain Structure ◽  
Random Copolymers ◽  
Multiblock Copolymers ◽  
Structure Property ◽  
Reaction Conditions ◽  
Property Relations ◽  
Cross Metathesis

We investigate the structure–property relations of the multiblock copolymers of norbornene with cyclododecene synthesized via the macromolecular cross-metathesis reaction between amorphous polynorbornene and semicrystalline polydodecenamer in the presence of the first-generation Grubbs catalyst. By adjusting the reaction time, catalyst amount, and composition of the initial system, we obtain a set of statistical multiblock copolymers that differ in the composition and average length of norbornene and dodecenylene unit sequences. Structural, thermal, and mechanical characterization of the copolymers with NMR, XRD, DSC (including thermal fractionation by successive self-nucleation and annealing), and rotational rheology allows us to relate the reaction conditions to the average length of crystallizable unit sequences, thicknesses of corresponding lamellas, and temperatures of their melting. We demonstrate that isolated dodecenylene units can be incorporated into crystalline lamellas so that even nearly random copolymers should retain crystallinity. Weak high-temperature endotherms observed in the multiblock copolymers of norbornene with cyclododecene and other cycloolefins could indicate that the corresponding systems are microphase-separated in the melt state.

scholarly journals Characteristics and mechanical properties changes due to incorporation of aloe vera in polyethylene-based film

2020 ◽  
Vol 17 (2) ◽  
pp. 61
Author(s):  
Siti Fatma Abd Karim ◽  
Junaidah Binti Jai ◽  
Ku Halim Ku Hamid ◽  
Abdul Wafi Abdul Jalil
Keyword(s):  
Mechanical Properties ◽  
Thermal Degradation ◽  
Aloe Vera ◽  
Functional Materials ◽  
Chain Structure ◽  
Substantial Effect ◽  
Scanning Calorimetry ◽  
Degradation Temperature ◽  
And Performance ◽  
The Impact

Non-degradable properties of polyethylene (PE) films due to long-chain structure cause increment of solid waste plastic. Many researchers, with different purposes, have studied the incorporation of functional materials to PE. Studying the impact of incorporation of aloe vera (AV) into PE films in terms of its characteristic and mechanical properties is the main objective of this paper. The films were prepared using melt-blending and hot press technique. The characterization assessed for the PE and PE-AV films were spectroscopy, crystalline phase, thermal analysis and performance of mechanical properties of the sample.  The functional group detected in spectroscopy studied did not show any changes for PE film or PE with the presence of AV. Lower thermal degradation temperature (Td) obtained for PE-AV3 while others film found no significant changes of Td value and only one peak of thermal degradation occurred for all film. The same goes to the analysis obtained from differential scanning calorimetry (DSC) data. However, the crystalline structure displayed momentous peak changes for PE with AV. The highest tensile strength (TS) obtained by PE-AV3, at once developing highest value of Young’s modulus (YM), modulus of resilience (UE) and modulus of toughness (UT). A certain amount of AV has substantial effect on changing the polymeric structure especially improving the mechanical properties of PE film. Therefore, AV has potential to become an additive for developing a new partially degradable PE film.

System Dynamics and Disk Drive Head Position Error Prediction in a Data Storage Box

2014 ◽  
Author(s):  
Lidu Huang ◽  
Chiao-ping Roger Ku ◽  
Jean O’Young ◽  
Toshiki Hirano
Keyword(s):  
Data Storage ◽  
Storage System ◽  
Disk Drive ◽  
Head Position ◽  
Position Error ◽  
System Level ◽  
Disk Drives ◽  
Data Storage System ◽  
Mechanical Disturbances ◽  
System Transfer Function

Disk drives are packed at ever dense arrangement in a modern data storage system, internal and external mechanical disturbances can have a great effect to disk drive’s read and write performances. The VCM torque generated during seeking affects its own as well as neighboring drives head position. In this study, we modeled a storage box with multiple HDDs installed to obtain mechanical system transfer function. The mechanical excitation is characterized by VCM torque, and HDD operational vibration behaviors on linear and rotational shakers are measured. A system level hybrid method predicting HDD head position error in a data storage box is described, and both analytical and measured results will be presented.

Scanning probe-type data storage beyond hard disk drive and flash memory

MRS Bulletin ◽  
2018 ◽  
Vol 43 (5) ◽  
pp. 365-370 ◽  
Author(s):  
Yasuo Cho ◽  
Seungbum Hong
Keyword(s):  
Hard Disk Drive ◽  
Data Storage ◽  
Flash Memory ◽  
Hard Disk ◽  
Disk Drive ◽  
Scanning Probe ◽  
Probe Type ◽  
Type Data ◽  
Image Position

Abstract

Managing Granularity in Design and Implementation of Geospatial Web Services

2011 ◽  
pp. 18-35 ◽  
Author(s):  
Elias Z. K. Ioup ◽  
John T. Sample
Keyword(s):  
Web Services ◽  
Data Storage ◽  
User Needs ◽  
Design Decisions ◽  
Design And Implementation ◽  
Performance Requirements ◽  
And Performance ◽  
Geospatial Services ◽  
Geospatial Web Services

Granularity is often ignored when designing geospatial Web services. Choices relating to granularity affect service interfaces, data storage and organization, and XML format design. This chapter highlights the importance of analyzing usage and performance requirements when deciding on granularity choices in the design of geospatial Web services. Often, instead of making design decisions based on these requirements, geospatial services are implemented using default, commonly used techniques which may reduce performance, increase complexity, or fail to fully meet user needs. This chapter discusses the importance of granularity in designing and implementing geospatial Web services and provides common examples that highlight the different approaches to granularity which are available.

scholarly journals Demethylation of Alkali Lignin with Halogen Acids and Its Application to Phenolic Resins

Polymers ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 1771 ◽  
Author(s):  
Hao Wang ◽  
Thomas L. Eberhardt ◽  
Chunpeng Wang ◽  
Shishuai Gao ◽  
Hui Pan
Keyword(s):  
1H Nmr ◽  
Nucleophilic Reagent ◽  
2D Nmr ◽  
Hydroxyl Groups ◽  
Chemical Processing ◽  
Hydroxyl Content ◽  
Phenolic Resins ◽  
Alkali Lignin ◽  
Ft Ir ◽  
And Performance

Lignin, a byproduct from the chemical processing of lignocellulosic biomass, is a polyphenolic compound that has potential as a partial phenol substitute in phenolic adhesive formulations. In this study, HBr and HI were used as reagents to demethylate an alkali lignin (AL) to increase its hydroxyl content and thereby enhance its reactivity for the preparation of phenolic resins. Analyses by FT-IR, 1H-NMR and 2D-NMR(HSQC) demonstrated both a decrease in methoxyl groups and an increase in hydroxyl groups for each demethylated lignin (DL). In addition, the molar amounts of phenolic hydroxyls, determined by 1H-NMR, increased to 0.67 mmol/g for the HI-DL, and 0.64 mmol/g for the HBr-DL, from 0.52 mmol/g for the AL. These results showed that HI, a stronger nucleophilic reagent than HBr, provided a higher degree of AL demethylation. Lignin-containing resins, prepared by copolymerization, met the bonding strength standard for exterior plywood with DL used to replace as much as 50 wt.% of phenol. The increased hydroxyl contents resulting from the lignin demethylations also imparted faster cure times for the lignin-containing resins and lower formaldehyde emissions. Altogether, the stronger nucleophilicity of HI, compared to HBr, impacted the degree of lignin demethylation, and carried through to measurable differences the thermal properties and performance of the lignin-containing PF resins.

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