Emission Characteristics of PVK Doped TbY(o-MBA)_6(phen)_2 Systems

A rare earth complex TbY （o-MBA）6（phen）2 was synthesized, which was first used as an emitting material in electroluminescence. By doping it into the conjugated polymer PVK, single-layer and double-layer devices were fabricated with structures： device A ： ITO/PVK ： rpDY （o-MBA）6（phen）2/LiF/Al; B ： ITO/PVK ： rpDY （o-MBA）6（phen）2/AIQ/LiF/Al; C： ITO/PVK： TbY（o-MBA）6（phen）2/BCP/AlQ/LiF/Al. The characteristics of these devices were investigated. For single-layer and double-layer devices, the emission of PVK was completely restrained, and only the green emission from rpD^3＋ was observed in electroluminescence. The above mentioned observation is attributed to the different mechanism of electroluminescence and photoluminescence. In photoluminescence process, the energy of Tb complex may come from PVK through Forster energy transfer process, while in electroluminescence process direct sequential charge trapping appeares to be the main operating mechanism. From the optimized device B, brightly green emission can be obtained, and the highest EL brightness of the device reaches 213 cd·m^-2 at 14 V.

SRSC: Improving Restore Performance for Deduplication-Based Storage Systems

Modern backup systems exploit data deduplication technology to save stor-age space whereas suffering from the fragmentation problem caused by deduplication.Fragmentation degrades the restore performance because of restoring the chunks thatare scattered all over different containers. To improve the restore performance, thestate-of-the-art History Aware Rewriting Algorithm(HAR) is proposed to collect frag-mented chunks in the last backup and rewrite them in the next backup. However, dueto rewriting fragmented chunks in the next backup, HAR fails to eliminate internalfragmentation caused by self-referenced chunks(that exist more than two times in abackup) in the current backup, thus degrading the restore performance. In this paper,we propose Selectively Rewriting Self-Referenced Chunks(SRSC), a scheme that de-signs a buffer to simulate a restore cache, identify internal fragmentation in the cacheand selectively rewrite them. Our experimental results based on two real-world datas-ets show that SRSC improves the restore performance by 45% with an acceptable sac-rifice of the deduplication ratio.

Organic Light Emitting Devices Based on Terbium Complex

Rare earth complex TbY(m-MOBA)_6(phen)_2·2H_2O was synthesized, which was first used as an emitting material in electroluminescence. The properties of monolayer device with the rate of 1000 r·min^(-1) (70 nm) and the impure concentration of 1∶5 were the best. And the highest brightness of this device reached 21.8 cd·cm^(-2) at a fixed bias of 20 V. Bright green emission can be obtained from the optimized double-layer device, and the highest EL brightness of the device reached 289 cd·m^(-2) at the voltage of 21 V.

Non-sequential striping encoder from replication to erasure coding for distributed storage system

1 Introduction and main contributions As so many machines are clustered in datacenters,failures occur frequently[1,2].Redundancy schemes,like replication and erasure coding,are deployed to store redundant data to tolerate failures.For distributed systems with these two redundancy schemes,new data are hot in replication,and usually turn cold as time goes by.An encoder performing the conversion can cause large overheads on network and put data in low reliability when the encoder is not well designed.

Organic Light-Emitting Device Based on Terbium Complex

A new rare earth complex Tb(p-MBA)_3phen was synthesized, which is first used as an emitting material in organic electroluminescence. By doping it into the conjugated polymer PVK, single-layer and double-layer devices were fabricated with structures: device 1: ITO/PVK∶Tb(p-MBA)_3phen/Al; device 2∶ ITO/PVK: Tb(p-MBA)_3phen/AlQ/LiF/Al. The characteristics of these devices have been investigated. The emission of PVK is completely restrained, and only the pure green emission from Tb^(3+) can be observed in electroluminescence. The optimized device 2 has better monochromatic characteristics with the maximal brightness of 152 cd·m^(-2) at the voltage of 20 V.

Organic Light-Emitting Devices Based on Terbium Complex

Rare earth complex with a structure of [Tb(m-MBA)_3phen]_2·2H_2O was synthesized,which was used as light-emitting material in electroluminescence. The terbium complex was dispersed in poly (N-vinylcarbazole) (PVK) as an emitting layer which is made by spin coating. Two kinds of devices were fabricated with structures: as following device Ⅰ: glass/ITO/PVK: terbium complex/PBD/LiF/Al, and device Ⅱ: glass/ITO/PVK: terbium complex/AlQ/LiF/Al. The photoluminescent (PL) and electroluminescent (EL) behaviors of the devices were investigated. Bright green emission can be obtained from optimized device Ⅱ,and the highest EL brightness of it reaches 140 cd·m (-2) at the voltage of 20 V.

Fractional density of states and the overall spontaneous emission control ability of a three-dimensional photonic crystal

Fractional density of states(FDOS) hinders the accurate measuring of the overall spontaneous emission(SE)control ability of a three-dimensional(3 D) photonic crystal(PC) with the current widely used SE decay lifetime measurement systems. Based on analyzing the FDOS property of a 3 D PC from theory and simulation,the excitation focal spot position averaged FDOS with a distribution broadening parameter was proposed to accurately reflect the overall SE control ability of the 3 D PC. Experimental work was done to confirm that our proposal is effective, which can contribute to comprehensively characterizing the SE control performance of photonic devices with quantified parameters.

Enhancing security of NVM-based main memory with dynamic Feistel network mapping

As promising alternatives in building future main memory systems, emerging non-volatile memory(NVM) technologies can increase memory capacity in a cost-effective and power-efficient way. However, NVM is facing security threats due to its limited write endurance: a malicious adversary can wear out the cells and cause the NVM system to fail quickly. To address this issue, several wear-leveling schemes have been proposed to evenly distribute write traffic in a security-aware manner. In this study, we present a new type of timing attack, remapping timing attack(RTA), based on information leakage from the remapping latency difference in NVM. Our analysis and experimental results show that RTA can cause three of the latest wear-leveling schemes(i.e., region-based start-gap,security refresh, and multi-way wear leveling) to lose their effectiveness in several days(even minutes), causing failure of NVM. To defend against such an attack, we further propose a novel wear-leveling scheme called the ‘security region-based start-gap(security RBSG)', which is a two-stage strategy using a dynamic Feistel network to enhance the simple start-gap wear leveling with level-adjustable security assurance. The theoretical analysis and evaluation results show that the proposed security RBSG not only performs well when facing traditional malicious attacks, but also better defends against RTA.

An efficient memory data organization strategy for application-characteristic graph processing

1 Introduction Graph processing has received significant attention for its ability to cope with large-scale and complex unstructured data in the real-world.However,most of the graph processing applications exhibit an irregular memory access pattern which leads to a poor locality in the memory access stream[1].

A high-performance and endurable SSD cache for parity-based RAID

Solid-state drives (SSDs)have been widely used as caching tier for disk-based RAID systems to speed up dataintensive applications.However,traditional cache schemes fail to effectively boost the parity-based RAID storage sys- tems (e.g.,RAID-5/6),which have poor random write performance due to the small-write problem.What's worse,intensive cache writes can wear out the SSD quickly,which causes performance degradation and cost increment.In this article,we present the design and implementation of KDD, an efficient SSD-based caching system which Keeps Data and Deltas in SSD.When write requests hit in the cache, KDD dispatches the data to the RAID storage without updating the parity blocks to mitigate the small write penalty, and compactly stores the compressed deltas in SSD to reduce the cache write traffic while guaranteeing reliability in case of disk failures.In addition,KDD organizes the metadata partition on SSD as a circular log to make the cache persistent with low overhead.We evaluate the performance of KDD via both simulations and prototype implementations.Experimental results show that KDD effectively reduces the small write penalty while extending the lifetime of the SSD-based cache by up to 6.85 times.

Write-Optimized B^(+) Tree Index Technology for Persistent Memory

Due to its low latency,byte-addressable,non-volatile,and high density,persistent memory(PM)is expected to be used to design a high-performance storage system.However,PM also has disadvantages such as limited endurance,thereby proposing challenges to traditional index technologies such as B(+)tree.B(+)tree is originally designed for dynamic random access memory(DRAM)-based or disk-based systems and has a large write amplification problem.The high write amplification is detrimental to a PM-based system.This paper proposes WO-tree,a write-optimized B(+)tree for PM.WO-tree adopts an unordered write mechanism for the leaf nodes,and the unordered write mechanism can reduce a large number of write operations caused by maintaining the entry order in the leaf nodes.When the leaf node is split,WO-tree performs the cache line flushing operation after all write operations are completed,which can reduce frequent data flushing operations.WO-tree adopts a partial logging mechanism and it only writes the log for the leaf node.The inner node recognizes the data inconsistency by the read operation and the data can be recovered using the leaf node information,thereby significantly reducing the logging overhead.Furthermore,WO-tree adopts a lock-free search for inner nodes,which reduces the locking overhead for concurrency operation.We evaluate WO-tree using the Yahoo!Cloud Serving Benchmark(YCSB)workloads.Compared with traditional B(+)tree,wB-tree,and Fast-Fair,the number of cache line flushes caused by WO-tree insertion operations is reduced by 84.7%,22.2%,and 30.8%,respectively,and the execution time is reduced by 84.3%,27.3%,and 44.7%,respectively.