Disk Block Research Articles

"Cell Disk" DNA Storage System Capable of Random Reading and Rewriting.

DNA has emerged as an appealing material for information storage due to its great storage density and durability. Random reading and rewriting are essential tasks for practical large-scale data storage. However, they are currently difficult to implement simultaneously in a single DNA-based storage system, strongly limiting their practicability. Here, a "Cell Disk" storage system is presented, achieving high-density in vivo DNA data storage that enables both random reading and rewriting. In this system, each yeast cell is used as a chamber to store information, similar to a "disk block" but with the ability to self-replicate. Specifically, each genome of yeast cell has a customized CRISPR/Cas9-based "lock-and-key" module inserted, which allows selective retrieval, erasure, or rewriting of the targeted cell "block" from a pool of cells ("disk"). Additionally, a codec algorithm with lossless compression ability is developed to improve the information density of each cell "block". As a proof of concept, target-specific reading and rewriting of the compressed data from a mimic cell "disk" comprising up to 105 "blocks" are demonstrated and achieve high specificity and reliability. The "Cell Disk" system described here concurrently supports random reading and rewriting, and it should have great scalability for practical data storage use.

Identification of Stribeck Model Parameters to Accurately Reveal Stick–Slip Characteristics of a Disc–Block Friction System

Stick–slip vibration is simultaneously influenced by several factors that share complicated coupling relationships. In this research, an experimental investigation was performed to analyze the evolution law of stick–slip characteristics at different working conditions using a tribometer. The results showed that the disc rotational speed and normal force had noticeable impact on both stick–slip vibration and coefficient of friction (COF). Then the Stribeck model, which can characterize COF characteristics in the stick–slip process, was employed and the parameters were identified to construct a dynamic relationship between working conditions and COF. Further, numerical simulations respectively considering and neglecting the dynamic relationship between working conditions and Stribeck model parameters were conducted via an established tribometer analytical model. It was found that the simulation results considering the influence of working conditions on Stribeck model parameters were in better agreement with the experimental results, as the stick–slip vibration depends on the combined effect of working conditions and Stribeck model parameters. Therefore, the dynamic relationship between working conditions and Stribeck model parameters is crucial to accurately reveal stick–slip characteristics.

Dynamic response analysis of a train braking system with time-varying coefficient of friction excitations

Coefficient of friction (COF) is a key parameter that reflects the interface tribological behavior and influences the system dynamic response. In this research, the tribological properties of the train braking system friction blocks with different perforation diameters are experimentally explored using a block-on-disc apparatus. And the distribution law of the interface COF is revealed by statistical analysis. It is found that the histogram of the COF approximately follows a normal distribution. Considering the time-varying of the COF, a time-varying COF model is then established based on the normal distribution parameters. Further, the time-varying COF model is integrated into a proposed train braking system numerical model to construct the association between the disc–block friction properties and the braking system dynamic response. Based on this, the dynamic behavior of the braking system subject to interface time-varying COF excitations and block perforation structure is analyzed. The results show the time-varying COF excitations should be considered to accurately reveal the dynamic response of the braking system. Moreover, the friction block processed a perforation diameter of 2 mm obviously reduces disc–block friction vibration and improves the stability of the train braking system.

Evaluation of the dynamic behaviors of a train braking system considering disc–block interface characteristics

Disc–block interface properties have prominent influence on the dynamic behaviors of train braking systems. In this study, the tribological characteristics of small-scale train friction blocks with different perforation diameters at the centre of the block surface were investigated using a disc–block test rig. And the Stribeck model parameters of the disc–block friction interface were identified to intuitively characterize the evolution law of stick–slip characteristics with the variation of block perforation diameters. Then, a trailer bogie braking system model of a high-speed train considering the coupling effects between the essential brake unit, wheelset and bogie frame was established. And the identified Stribeck parameters were introduced into the proposed braking system dynamics model to establish a relationship between the friction characteristics of the disc–block interface and the dynamic behaviors of the train braking system. Based on this, the cross-scale analysis was performed to evaluate the dynamic performance of a train braking system affected by the perforated friction block via classical stability theory and numerical simulation. The results show that the friction block with a perforation diameter of 3 mm can effectively suppress the stick–slip vibration of the disc–block friction interface, then reducing the oscillation of system components and enhancing the stability of the entire trailer bogie system.

Stick–Slip Characteristic Analysis of High-Speed Train Brake Systems: A Disc–Block Friction System with Different Friction Radii

Inspired by the difference in the friction radii of the pads from the high-speed train brake system, stick–slip experiments for a disc–block friction system with different friction radii were carried out via a test device. Based on the test results, the stick–slip vibration characteristics of the disc–block friction system with variation in the friction radius were analyzed, and the corresponding Stribeck model parameters in exponential and fractional forms were identified. The experimental results show that with an increase in the friction radius the vibration amplitude first increased and then decreased and the frequency of stick–slip vibration increased. The identified Stribeck model parameters show that the decay factors increased, the static friction coefficient decreased, and the dynamic friction coefficient decreased first and then increased as the friction radius increased. Moreover, the identified Stribeck model in an exponential form can more accurately reflect the stick–slip characteristics of a disc–block friction system than the model in a fractional form. It can be further applied in the investigation of the dynamic behaviors of high-speed train brake systems.

A linear algorithm for semi-external cutnode computation

In the literature, many algorithms have been proposed for finding cutnodes on undirected graphs, since cutnodes are crucial to graph connectivity. Here, a cutnode of an undirected graph G is a node of G, whose deletion will cause a reachable pair of the other nodes in G to be unreachable. Currently, the difficulty of maintaining the entire G in the main memory makes researchers pay attention to compute cutnodes on semi-external memory model. This paper shows that traditional semi-external algorithms are limited by their unbounded time and I/O consumption, making them impractical when G is relatively large or complex. Thus, we propose a linear semi-external cutnode computation algorithm, named SECN. Assuming that G has n nodes and m edges, and B is the disk block size. SECN is the first that can find all the cutnodes of G in O(m+n) time and with O(mB) I/O cost on the semi-external memory model, as far as we know. SECN also has a smaller minimum memory space requirement than traditional algorithms. Our experimental evaluation conducted on both synthetic and real graphs confirms that SECN significantly outperforms existing algorithms (up to 103 times faster).

Two Cases of Iatrogenic Lumbar Foraminal Disc Herniations

Objective We report two cases of iatrogenic deterioration of lumbar foraminal disc herniations following lumbar disc injections. Summary of Background Data. Complications associated with discography were reported. However, only a few reports have thus far referred to the iatrogenic deterioration of lumbar foraminal disc herniations. Cases 60-year-old and 74-year-old men were treated with MR images of L4-5 foraminal disc herniations without fragment in the spinal canal. The patients underwent discography and disc block for its diagnosis and treatment. After disc injections, both patients complained of deterioration of L4 radiculopathy. Results On disco-CT or reexamined MR images after disc injections, herniated fragment was migrated from neural foramen to cranial central spinal canal with was not shown in previous MR images. The herniated fragments were extirpated by means of osteoplastic laminoplasty or transforaminal lumbar interbody fusion with facetectomy. The herniated fragments were migrated from neural foramen to cranial central spinal canal. Conclusions The injection of liquid medicine into the nucleus led the intradiscal pressure increased, and the disc fragment might prolapsed through the raptured region of annulus fibrosus and migrated to cranial central spinal canal by anatomical reason. The disc injection may have a risk for deterioration of foraminal disc herniation. Our report is instructive for the management of discography for the diagnosis of foraminal disc herniations.

Intraosseous Radiofrequency Ablation of the Basivertebral Nerve in Chronic Low Back Pain: A Meta-Analysis

Purpose: To review the literature on the value of basivertebral nerve abla-tion in the treatment of chronic low back pain. Materials and Method: A systematic review and meta-analysis of the English literature to March 2020 was undertaken. The inclusion criteria were patients with discogenic back pain of more than 3 months duration with modic type 1 or 2 change and suc-cessful disc block or discogram. Primary outcomes were VAS pain, ODI, EQ-5D and SF36 improvement. Secondary outcomes were complications. Results: 6 studies were included, all funded by the same company, but oth-erwise of low bias. All studies showed significant improvement in all scores over the first 3 months with evidence these would be maintained over the longer term. There was one reported compression fracture, but otherwise no significant adverse events. Conclusion: This study supports the conclusion that radiofrequency ablation of the basivertebral nerve is a safe and effective treatment for discogenic chronic low back pain.

Efficient Out-of-Core and Out-of-Place Rectangular Matrix Transposition and Rotation

Modern computers keep following the traditional model of addressing memory linearly for their main memory and out-of-core storage. While this model allows efficient row access to row-major 2D matrices, it introduces complexity to perform efficient column access. A common strategy to improve these accesses is to transpose or rotate the matrix beforehand, thus the accessing complexity is centralized in one transformation operation. Further column accesses are performed as row accesses to the transposed matrix therefore they are optimized to the memory model. In this article, we propose an efficient solution to perform in-memory or out-of-core rectangular matrix transposition and rotation by using an out-of-place strategy, reading a matrix from an input file and writing the transformed matrix to another (output) file. An originality of our processing algorithm is to rely on an optimized use of the page cache mechanism. It is parallel, optimized by several levels of tiling and independent of any disk block size. We evaluate our approach on five common storage configurations: HDD, hybrid HDD-SSD, SSD, software RAID 0 of several SSDs, and NVMe. We show that it brings significant performance improvement over a hand-tuned optimized reference implementation developed by the Caldera company and we confront it against the baseline speed of a straight file copy.

PNG Data Detector for DECA

DECA, a novel file carving application, is an example of digital forensic tools that rely heavily on accurately detecting the type of data fragments stored in the disk blocks. This work is an attempt to create a method of detection and classification of PNG data types for DECA which originally only identifies and extracts JPEG data. The PNG file format was examined in order to implement the PNG data detector that was integrated into DECA. We then examined the results of decision-theoretic file carving, implemented in DECA, combined with the implemented PNG data detector.

Bentonite buffer blocks manufactured by isostatic compression

Isostatic compression is a technically highly specialised technology for manufacturing solid components from powder. There are only few reported experiences for isostatic compression of bentonite clay, which forms the basis of the engineered barrier system in the geological disposal concept KBS-3V, currently under investigation in Sweden and Finland. An isostatically compressed middle-scale MX-80 bentonite ring block (approximately 2/3 of full-scale diameter) was examined with regard to its dimensions, shape and surface texture. The physical and mechanical characteristics of the middle-scale ring block were analysed. The measured results were compared to previously obtained data from other isostatically compacted disc and ring blocks of similar scale, as well as to a full-scale ring block also manufactured by isostatic compression. Irrespective of the different manufacturing conditions, a consistent homogeneity among the middle-scale blocks and between the middle and full-scale blocks was determined. Results show that isostatic compression is a feasible manufacturing method that meets the high technical standards demanded in nuclear waste management.

CBase: Fast Virtual Machine storage data migration with a new data center structure

Live Virtual Machine (VM) migration within a data center is an important technology for cloud management, and has brought many benefits to both cloud providers and users. With the development of cloud computing, across-data-center VM migration is also desired. Normally, there is no shared storage system between data centers, hence the storage data (disk image) of a VM will be migrated to the destination data center as well. However, the slow network speed of the Internet and the comparatively large size of VM disk image make VM storage data migration become a bottleneck for live VM migration across data centers. In this paper, based on a detailed analysis of VM deployment models and the nature of VM image data, we design and implement a new migration system, called CBase. The key concept of CBase is a newly introduced central base image repository for reliable and efficient data sharing between VMs and data centers. With this central repository, further performance optimizations to VM storage data migration are made possible. Two migration mechanisms (data deduplication and Peer-to-Peer (P2P) file sharing) are utilized to accelerate base image migration, and a strategy is designed to elevate the synchronization of newly-written disk blocks. The results from an extensive experiment show that CBase significantly outperforms existing migration mechanisms under different conditions regarding total migration time and total network traffic. In particular, CBase with data deduplication is better than P2P file sharing for base image migration in our experimental environment.

Building an Optimal Point-Location Structure in $$O( sort (n))$$ O ( s o r t ( n ) ) I/Os

We revisit the problem of constructing an external memory data structure on a planar subdivision formed by n segments to answer point location queries optimally in $$O(\log _B n)$$ I/Os. The objective is to achieve the I/O cost of $$ sort (n) = O(\frac{n}{B} \log _{M/B} \frac{n}{B})$$ , where B is the number of words in a disk block, and M being the number of words in memory. The previous algorithms are able to achieve this either in expectation or under the tall cache assumption of $$M \ge B^2$$ . We present the first algorithm that solves the problem deterministically for all values of M and B satisfying $$M \ge 2B$$ .

Content Look-Aside Buffer for Redundancy-Free Virtual Disk I/O and Caching

Storage consolidation in a virtualized environment introduces numerous duplications in virtual disks and imposes considerable pressure on disk I/O and caching. In this paper, we present a content look-aside buffer (CLB) approach for simultaneously providing redundancy-free virtual disk I/O and caching. CLB attaches persistent fingerprints to virtual disk blocks, which enables detection of I/O redundancy before disk access. At run time, CLB exploits content pages already present in the guest disk caches to service the redundant reads through page sharing, thus eliminating both redundant I/O requests and redundant disk cache copies. For write requests, CLB uses a group invalidating writeback protocol for updating fingerprints to support crash consistency while minimizing disk write overhead. By implementing and evaluating a CLB prototype on KVM hypervisor, we demonstrate that CLB delivers considerably improved I/O performance with realistic workloads. Our CLB prototype improves the throughput of sequential and random read on duplicate data by 4.1x and 26.2x, respectively. For typical read-intensive workloads, such as booting VM and launching application, CLB's I/O deduplication and cache deduplication eliminates 94.9%--98.5% of read requests and saves 50%--100% cache memory in each VM, respectively. Compared with the QEMU's raw virtual disk format, CLB improves the per-disk VM density by 8x--16x. For mixed read-write workloads, the cost of on-line fingerprint updating offsets the read benefit; nevertheless, CLB substantially improves overall performance.

Northern Bobwhite Survival Related to Movement on a Reclaimed Surface Coal Mine

Reclaimed coal mines represent opportunity to provide large tracts of early succession habitat essential to northern bobwhite (Colinus virginianus) populations. However, little research has been conducted to explore the potential of reclaimed mine sites and examine bobwhite ecology on these unique areas. Reclaimed mines in Kentucky were planted to non-native species, such as sericea lespedeza (Lespedeza cuneata) and tall fescue (Festuca arundinacea), which do not provide suitable structure for northern bobwhite brood-rearing and movement. Fallow disking (in blocks and linear firebreaks) and planting food plots are part of current management efforts to improve food availability and habitat structure for broods. We trapped and radiomarked 266 northern bobwhites between April 2010 and September 2011 on Peabody Wildlife Management Area, a 3,330-ha reclaimed coal mine in western Kentucky, USA to investigate the effects of current management practices on movement and survival. We calculated seasonal daily movement as the Euclidean distance from a location on day 1 to day 2. Breeding season (1 Apr-30 Sep) movement averaged 128 m in 2010 and 147 m in 2011. Daily movement averaged 163 m during the 2010–2011 non-breeding (1 Oct-31 Mar) season. Multiple regression analysis indicated annual food plots, disk blocks, firebreaks, and roads did not explain variation within daily movement regardless of season (R2 0.04). Individual bird/covey, precipitation, hours between locations, and average temperature also poorly explained movement variation. We used Program MARK to model the effect of season, year, mean daily movement, mean distance to annual food plots, disk blocks, firebreaks, and roads on survival. The season (breeding/non-breeding) model explained 81% of the variation in survival, and the year model explained 13%, suggesting management was not driving survival. We do not believe disking should be discontinued, although it did not influence movement, as it can improve vegetation structure important to nest-site selection and broods.

Isolated Storage of Multi-Tenant Data Based on Shared Schema

Abstract Multi-tenant data management is an important part of supporting efficient operation of software as a service application. Multi-tenant data use shared schema to reduce resource usage cost. However, massive data of different tenants are stored in the same schema, which causes useless data of other tenants to be read when a tenant just need access its own disk data. In this paper we focus on disk storage method of multi-tenant data based on shared schema to address the above low efficiency of data access. According to isolation requirement of multitenant data, we store a tenant’s data in some contiguous disk blocks. The experimental results illustrate that query efficiency in range query and join query is 1.5–2 times the existing storage method, and no indexing query efficiency improves 10–70 times.

B-Trees and Cache-Oblivious B-Trees with Different-Sized Atomic Keys

Most B-tree articles assume that all N keys have the same size K , that f = B / K keys fit in a disk block, and therefore that the search cost is O (log f + 1 N ) block transfers. When keys have variable size, B-tree operations have no nontrivial performance guarantees, however. This article provides B-tree-like performance guarantees on dictionaries that contain keys of different sizes in a model in which keys must be stored and compared as opaque objects. The resulting atomic-key dictionaries exhibit performance bounds in terms of the average key size and match the bounds when all keys are the same size. Atomic-key dictionaries can be built with minimal modification to the B-tree structure, simply by choosing the pivot keys properly. This article describes both static and dynamic atomic-key dictionaries. In the static case, if there are N keys with average size K , the search cost is O (⌈ K / B ⌉log 1 + ⌈ B / K ⌉ N ) expected transfers. It is not possible to transform these expected bounds into worst-case bounds. The cost to build the tree is O ( NK ) operations and O ( NK/B ) transfers if all keys are presented in sorted order. If not, the cost is the sorting cost. For the dynamic dictionaries, the amortized cost to insert a key κ of arbitrary length at an arbitrary rank is dominated by the cost to search for κ. Specifically, the amortized cost to insert a key κ of arbitrary length and random rank is O (⌈ K / B ⌉log 1 + ⌈ B / K ⌉ N + |κ|/ B ) transfers. A dynamic-programming algorithm is shown for constructing a search tree with minimal expected cost. This article also gives a cache-oblivious static atomic-key B-tree, which achieves the same asymptotic performance as the static B-tree dictionary, mentioned previously. A cache-oblivious data structure or algorithm is not parameterized by the block size B or memory size M in the memory hierarchy; rather, it is universal, working simultaneously for all possible values of B or M . On a machine with block size B , if there are N keys with average size K , search operations costs O (⌈ K / B ⌉log 1 + ⌈ B / K ⌉ N ) block transfers in expectation. This cache-oblivious layout can be built in O ( N log( NK )) processor operations.

Effects of Mechanical Wheel Slide Protection Devices Action on Railway Vehicles Braking Process

The paper investigates the effects of mechanical wheel slide protection devices (WSPD) on the braking capacity for coaches equipped with disc or cast iron block brakes. Decelerations and jerks, that affect the passengers comfort, are also analyzed. An original simulation program, based on experimentally determined air pressure evolutions in brake cylinder is used for this purpose. Results of numerical simulations show that in the case of repeated actuations of mechanical WSPDs, disc brake vehicles are more affected in terms of braking capacity. Regarding jerks during braking actions, in both normal and low adhesion conditions, vehicles equipped with high power cast iron block brake with two pressure levels prove to be more affected.

RailwayDB: adaptive storage of interaction graphs

We are living in an ever more connected world, where data recording the interactions between people, software systems, and the physical world is becoming increasingly prevalent. These data often take the form of a temporally evolving graph, where entities are the vertices and the interactions between them are the edges. We call such graphs interaction graphs. Various domains, including telecommunications, transportation, and social media, depend on analytics performed on interaction graphs. The ability to efficiently support historical analysis over interaction graphs requires effective solutions for the problem of data layout on disk. This paper presents an adaptive disk layout called the railway layout for optimizing disk block storage for interaction graphs. The key idea is to divide blocks into one or more sub-blocks. Each sub-block contains the entire graph structure, but only a subset of the attributes. This improves query I/O, at the cost of increased storage overhead. We introduce optimal integer linear program (ILP) formulations for partitioning disk blocks into sub-blocks with overlapping and nonoverlapping attributes. Additionally, we present greedy heuristics that can scale better compared to the ILP alternatives, yet achieve close to optimal query I/O. We provide an implementation of the railway layout as part of RailwayDB--an open-source graph database we have developed. To demonstrate the benefits of the railway layout, we provide an extensive experimental evaluation, including model-based as well as empirical results comparing our approach to baseline alternatives.

Efficient Storage Management over Cloud using Data Compression without Losing Searching Capacity

Nowadays due to social media, people may communicate with each other, share their thoughts and moments of life in form of texts, images or videos. We are uploading our private data in terms of photos, videos, and documents on internet websites like Facebook, Whatsapp, Google+ and Youtube etc. In short today world is surrounded with large volume of data in different form. This put a requirement for effective management of these billions of terabytes of electronic data generally called BIG DATA. Handling large data sets is a major challenge for data centers. The only solution for this problem is to add as many hard disk as required. But if the data is kept in unformatted the requirement of hard disk will be very high. Cloud technology in today is becoming popular but efficient storage management for large volume of data on cloud still there is a big question. Many frameworks are available to address this problem. Hadoop is one of them. Hadoop provides an efficient way to store and retrieve large volume of data. But Hadoop is efficient only if the file containing data is large enough. Basically Hadoop uses a big hard disk block to store data. And this makes it inefficient in the area where volume to data is large but individual file is small. To satisfy both challenges to store large volume of data in less space. And to store small unit of file without wasting the space. We require to store data not is usual form but in compressed form so that we can keep the block size small. But if we do so it added one more dimension of problem. Searching the content in a compressed file is very in-efficient. Therefore we require an efficient algorithm which compress the file without disturbing the search capacity of the data center. Here we will provide the way how we can solve these challenges. Keywords : Cloud, Big DATA, Hadoop, Data Compression, MapReduce