Random File Research Articles

Effects of correlations in uncertainties of total cross section and elastic angular distribution for a deep penetration of 14-MeV neutrons in Cu

ABSTRACT Uncertainty in neutron reaction rates after penetrating a thick copper benchmark assembly was estimated based on two different kinds of Total Monte Carlo methods under random sampling methodology. Five hundred random nuclear data files were generated for 63Cu by Bayesian Monte Carlo method by perturbing the underlying nuclear model parameters. In the first method, these files were used directly to generate processed libraries, preserving all the correlations among different physical quantities. In the second method, the random files generated in the first method were used, but the angular distributions of elastic scattering were kept fixed to those of the non-perturbed nominal one. It was found that the two methods have the same neutron reaction rate after 608 mm penetration of copper. However, the uncertainty of the first method was smaller than that of the second method. It shows that the correlation between angular distribution of elastic scattering at 0 degrees and total cross section, which stems from Wick’s inequality, affects uncertainty of the calculated neutron reaction rate. It could be concluded that the uncertainty obtained by using the covariance files given in the ENDF-6 format may not give correct results for the uncertainty of neutron penetration calculations.

Formula omitted]: Keyword-based auditing with frequency hiding and retrieval reliability for smart government

In a keyword-based auditing paradigm, users typically focus on specific parts of a dataset rather than the integrity of the dataset as a whole. However, this approach is subjective and can be exploited by malicious storage servers to analyze audit frequency or reduce backups. This poses a significant risk for government data, where any privacy leakage or corruption could have catastrophic consequences. In this paper, we propose a keyword-based auditing scheme for smart government called KA, which provides both frequency hiding and retrieval reliability. KA leverages a Bloom filter to adjust the false positive rate and audits files based on specified keywords and random files obtained through fuzzy matching. To obtain privacy-preserving fuzzy matching, KA constructs an index table embedded with update times to retrieve a wide range of files to be audited. This approach is secure against replay attacks and supports index table updates through structure iteration instead of recalculation. Additionally, KA uses a relation matrix to detect all challenged storage nodes and ensure honest storage proof. KA provides storage robustness, privacy protection of hidden frequencies, Data security and retrieval reliability. Furthermore, It reduces audit computation overhead by 32.6% compared to probabilistic public auditing.

Effect of correlation between cross sections and angular distributions in nuclear data of 63Cu on estimation of uncertainty of neutron penetration

Uncertainty in neutron reaction rates after penetrating a 608mm-thick copper benchmark experiment performed by the FNS facility of JAEA was estimated based on two different kinds of the Total Monte Carlo methods under random sampling methodology. 500 random nuclear data files were generated for 63Cu by the T6 code system with perturbing underlying model parameters. In the first method, these files were used directly to yield processed library preserving all the correlations among different physical quantities. In the second method, the random files populated by T6 were used but the angular distribution data were kept fixed to the non-perturbed nominal ones. It was found that the two methods gave the same neutron reaction rate after the 608 mm penetration of a copper, however uncertainty of the second method was larger than that of the first method. It shows that the correlation between total cross section and angular distribution of elastic scattering at 0 degree, which stems from Wick’s inequality, affects uncertainty of the calculated neutron reaction rate. The result is consistent with the case of 28Si on deep penetration of thick concrete problem previously reported by the authors. It could be concluded that the uncertainty obtained by using the covariance files given in the ENDF-6 format may not give correct results for the uncertainty of neutron penetration calculation.

StackZDPD: a novel encoding scheme for mass spectrometry data optimized for speed and compression ratio

As the pervasive, standardized format for interchange and deposition of raw mass spectrometry (MS) proteomics and metabolomics data, text-based mzML is inefficiently utilized on various analysis platforms due to its sheer volume of samples and limited read/write speed. Most research on compression algorithms rarely provides flexible random file reading scheme. Database-developed solution guarantees the efficiency of random file reading, but nevertheless the efforts in compression and third-party software support are insufficient. Under the premise of ensuring the efficiency of decompression, we propose an encoding scheme “Stack-ZDPD” that is optimized for storage of raw MS data, designed for the format “Aird”, a computation-oriented format with fast accessing and decoding time, where the core compression algorithm is “ZDPD”. Stack-ZDPD reduces the volume of data stored in mzML format by around 80% or more, depending on the data acquisition pattern, and the compression ratio is approximately 30% compared to ZDPD for data generated using Time of Flight technology. Our approach is available on AirdPro, for file conversion and the Java-API Aird-SDK, for data parsing.

Secure Storage Model for Digital Forensic Readiness

Securing digital evidence is a key factor that contributes to evidence admissibility during digital forensic investigations, particularly in establishing the chain of custody of digital evidence. However, not enough is done to ensure that the environment and access to the evidence are secure. Attackers can go to extreme lengths to cover up their tracks, which is a serious concern to digital forensics – particularly digital forensic readiness. If an attacker gains access to the location where evidence is stored, they could easily alter the evidence (if not remove it altogether). Even though integrity checks can be performed to ensure that the evidence is sound, the collected evidence may contain sensitive information that an attacker can easily use for other forms of attack. To this end, this paper proposes a model for securely storing digital evidence captured pre- and post-incident to achieve reactive forensics. Various components were considered, such as integrity checks, environment sandboxing, strong encryption, two-factor authentication, as well as unique random file naming. A proof-of-concept tool was developed to realize this model and to prove its validity. A series of tests were conducted to check for system security, performance, and requirements validation, Overall, the results obtained showed that, with minimal effort, securing forensic artefacts is a relatively inexpensive and reliable feat. This paper aims to standardize evidence storage, practice high security standards, as well as remove the need to create new systems that achieve the same purpose.

Crucial importance of correlation between cross sections and angular distributions in nuclear data of 28Si on estimation of uncertainty of neutron dose penetrating a thick concrete

ABSTRACT Uncertainty in neutron dose after penetrating a 3-m-thick concrete was estimated based on three different kinds of Total Monte Carlo methods under random sampling methodology. A thousand random nuclear data files were generated for 28Si by T6 by perturbing underlying model parameters. In the first method, these files were used directly to yield processed library preserving all the correlations among different physical quantities. In the second method, a covariance file in the ENDF-6 format was generated and 1000 random files were produced based on the covariance file. In the third method, the random files populated by T6 were used but the angular distribution data were kept fixed to non-perturbed nominal ones. It was found that the second and third methods gave equivalent variance of the neutron dose after deep penetration of a concrete, and this uncertainty was larger than the uncertainty given by the first method. It shows that the correlation between total cross section and angular distribution of elastic scattering affects uncertainty of the calculated neutron dose. It could be concluded that the uncertainty obtained by using the covariance files given in the ENDF-6 format may not give correct results for the uncertainty of deep penetration calculation.

Statistical Analysis of Tritium Breeding Ratio Deviations in the DEMO Due to Nuclear Data Uncertainties

For the stable and self-sufficient functioning of the DEMO fusion reactor, one of the most important parameters that must be demonstrated is the Tritium Breeding Ratio (TBR). The reliable assessment of the TBR with safety margins is a matter of fusion reactor viability. The uncertainty of the TBR in the neutronic simulations includes many different aspects such as the uncertainty due to the simplification of the geometry models used, the uncertainty of the reactor layout and the uncertainty introduced due to neutronic calculations. The last one can be reduced by applying high fidelity Monte Carlo simulations for TBR estimations. Nevertheless, these calculations have inherent statistical errors controlled by the number of neutron histories, straightforward for a quantity such as that of TBR underlying errors due to nuclear data uncertainties. In fact, every evaluated nuclear data file involved in the MCNP calculations can be replaced with the set of the random data files representing the particular deviation of the nuclear model parameters, each of them being correct and valid for applications. To account for the uncertainty of the nuclear model parameters introduced in the evaluated data file, a total Monte Carlo (TMC) method can be used to analyze the uncertainty of TBR owing to the nuclear data used for calculations. To this end, two 3D fully heterogeneous geometry models of the helium cooled pebble bed (HCPB) and water cooled lithium lead (WCLL) European DEMOs were utilized for the calculations of the TBR. The TMC calculations were performed, making use of the TENDL-2017 nuclear data library random files with high enough statistics providing a well-resolved Gaussian distribution of the TBR value. The assessment was done for the estimation of the TBR uncertainty due to the nuclear data for entire material compositions and for separate materials: structural, breeder and neutron multipliers. The overall TBR uncertainty for the nuclear data was estimated to be 3~4% for the HCPB and WCLL DEMOs, respectively.

A Dockers Storage Performance Evaluation: Impact of Backing File Systems

This paper reports on an in-depth examination of the impact of the backing filesystems to Docker performance in the context of Linux container-based virtualization. The experimental design was a 3x3x4 arrangement, i.e., we considered three different numbers of Docker containers, three filesystems (Ext4, XFS and Btrfs), and four application workloads related to Web server I/O activity, e-mail server I/O activity, file server I/O activity and random file access I/O activity, respectively. The experimental results indicate that Ext4 is the most optimal filesystem, among the considered filesystems, for the considered experimental settings. In addition, the XFS filesystem is not suitable for workloads that are dominated by synchronous random write components (e.g., characteristical for mail workload), while the Btrfs filesystem is not suitable for workloads dominated by random write and sequential write components (e.g., file server workload).

Uncertainty propagation based on correlated sampling technique for nuclear data applications

A correlated sampling technique has been implemented to estimate the impact of cross section modifications on the neutron transport and in Monte Carlo simulations in one single calculation. This implementation has been coupled to a Total Monte Carlo approach which consists in propagating nuclear data uncertainties with random cross section files. The TMC-CS (Total Monte Carlo with Correlated Sampling) approach offers an interesting speed-up of the associated computation time. This methodology is detailed in this paper, together with two application cases to validate and illustrate the gain provided by this technique: the highly enriched uranium/iron metal core reflected by a stainless-steel reflector HMI-001 benchmark, and the PETALE experimental programme in the CROCUS zero-power light water reactor.

Healthcare bricolage in Europe\u2019s superdiverse neighbourhoods: a mixed methods study

BackgroundStudies of the relationship between diverse populations, healthcare access and health outcomes have been dominated by approaches focusing on ethno-national groups or specific healthcare sectors. Healthcare bricolage conceptualises the processes by which individuals use multiple resources to address health concerns. It is relevant in superdiverse neighbourhoods with complex populations. This paper is original in its application of mixed methods to examine the extent to which, and the reasons why, individuals engage in healthcare bricolage.MethodsThe study utilized a parallel sequential methodology. Eight superdiverse neighbourhoods were selected, two in each of Bremen, Birmingham, Lisbon and Uppsala. Ethnographic research scoping the nature of each healthcare ecosystem was followed by 160 interviews (20 each neighbourhood) with a maximum variation sample of residents undertaken October 2015 to December 2016. Interviewees were asked to recall a health concern and describe actions taken to attempt resolution. Data was coded with a MAXQDA codebook checked for inter-coder reliability. Interview findings enabled identification of five types of bricolage, the nature of healthcare resources utilised and the factors which influenced residents’ tactics. Results were used to design a household survey using new questions and validated epidemiological instruments implemented January to October 2017. Respondents were identified using random address files and interviewed in person or by telephone. Multinomal logistic regressions were used to estimate the effect of changing the values of determinants on the probability of observing an outcome.ResultsAge, gender, level of education, migration background and extent of functional limitation were associated with bricolage tactics. Individuals demonstrating high levels of agency were more likely than those with low levels to engage in bricolage. Residents with high levels of trust in physicians were less likely to bricolage than those with lower levels of trust. Levels of health literacy showed no significant effects.ConclusionsThe nature and severity of health concern, trust in physicians and agency shaped residents’ bricolage tactics. The concept of bricolage enabled us to make visible the actions and resources utilised around public healthcare systems that would otherwise remain outwith healthcare access research. Actions were frequently undertaken via networks offering insights into healthcare-seeking behaviour.

Monte Carlo integral adjustment of nuclear data libraries – experimental covariances and inconsistent data

Integral experiments can be used to adjust nuclear data libraries. Here a Bayesian Monte Carlo method based on assigning weights to the different random files is used. If the experiments are inconsistent within them-self or with the nuclear data it is shown that the adjustment procedure can lead to undesirable results. Therefore, a technique to treat inconsistent data is presented. The technique is based on the optimization of the marginal likelihood which is approximated by a sample of model calculations. The sources to the inconsistencies are discussed and the importance to consider correlation between the different experiments is emphasized. It is found that the technique can address inconsistencies in a desirable way.

Total Monte Carlo acceleration for the PETALE experimental programme in the CROCUS reactor

The Bayesian Monte Carlo technics requires individual evaluations of random cross section files based on a Total Monte Carlo propagation. This article discusses the use of a Correlated Sampling acceleration applied to TMC calculations for experiments where a brute force technics is too expensive. An e_cient estimation of the reaction rate uncertainties in small dosimeters is obtained, together with the inter-dosimeter correlation associated to the cross section uncertainties.

Fog Radio Access Networks With Hierarchical Content Delivery

We investigate a novel hierarchical content delivery strategy for F-RAN in this paper to accommodate the acquisition of popular multimedia files. Particularly, the studied F-RAN is assumed to be formed by base stations (BSs), cache-enabled fog user equipments (F-UEs), and conventional cellular user equipments (C-UEs), where the BSs, F-UEs, and C-UEs are spatially distributed as independent HPPPs. Furthermore, we assume the presence of a multimedia content library F:= {1,2,...,F}. To facilitate the repetitive downloading of multimedia files in F for C-UEs, a novel hierarchical content delivery strategy, which comprises of the BS transmission phase and the F-UE transmission phase, is proposed. Particularly, under the proposed hierarchical content delivery strategy, a C-UE with a random file request is jointly and hierarchically served by its associated BS and the F-UEs within a distance of R d . Furthermore, to resolve the contentions among the F-UEs, a carrier sensing-based collision avoidance scheme is adopted in the F-UE transmission phase, and only the F-UEs which have the minimal back-off timer among their respective competitors are selected to deliver the cached file. As such, the proposed hierarchical content delivery strategy can substantially enhance the quality of experience of the F-RAN. In order to analyze the performance of the proposed hierarchical content delivery strategy, we derive the network successful content delivery probability of the F-RAN based on the HPPP approximation of active F-UEs. The simulation examples are presented to verify our analytical results.

Best Practices in Accessing Tape-Resident Data in HPSS*

Tape is an excellent choice for archival storage because of the capacity, cost per GB and long retention intervals, but its main drawback is the slow access time due to the nature of sequential medium. Modern enterprise tape drives now support Recommended Access Ordering (RAO), which is designed to reduce data recall/retrieval times. BNL SDCC's mass storage system currently holds more than 100 PB of data on tapes, managed by HPSS. Starting with HPSS version 7.5.1, a new feature called “Tape Order Recall (TOR) has been introduced. It supports both RAO and non-RAO drives. The file access performance can be increased by 30% to 60% over the random file access. Prior to HPSS 7.5.1, we have been using an in-house developed scheduling software, aka ERADAT. ERADAT accesses files based on the file logical position order. It has demonstrated a great performance over the past decade long usage in BNL. In this paper we will present a series of test results, compare TOR and ERADAT's performance under different configurations to show how effective TOR (RAO) and ERADAT perform and what is the best solution in data recall from SDCC's tape storage

Propagation of uncertainties in basic nuclear reaction data to uncertainties in the parameters of primary radiation damage by neutrons

The primary radiation damage formation in materials subjected to neutron radiation is very sensitive to the energy spectra of primary knock-on atoms (PKAs) and their collision cascade in the crystal lattice. The estimated values of the primary radiation damage metrics, such as displacements per atom (dpa) cross sections, integrated dpa, PKA spectrum and spectrum averaged PKA energy are uncertain because of uncertainties present in both the basic nuclear reaction data and the displacement damage model parameters. The Total Monte Carlo (TMC) methodology, which uses the random evaluated nuclear data files for nuclides, is well recognized to propagate the uncertainties in basic nuclear data to the derived quantities in nuclear reactor physics. The uncertainties in the above mentioned primary radiation damage parameters are obtained in this study by propagating the uncertainties in basic evaluated nuclear data, following the TMC methodology. The knowledge of uncertainties in the spectrum averaged PKA energies also enables us to ascertain the uncertainties in the production of vacancies through self-ion simulations using SRIM-2013 code. The present study is an outcome of our systematic approach towards establishing the procedure. This includes pre-processing a large number of TENDL nuclear data random files using NJOY-2016, developing an indigenous code CRaD for handling these point and multigroup data libraries and computing primary radiation damage metrics and their associated uncertainties including energy-energy and nuclear reaction channel-channel correlation matrices. The uncertainties in dpa cross sections and PKA spectra due to uncertainties in basic nuclear data are found to be comparatively larger than the uncertainties in respective integrated parameters; viz. dpa and average PKA energy. This study also confirms the non-Gaussian distributions of derived primary radiation damage parameters.

File Encryption and Hiding Application Based on AES and Append Insertion Steganography

Steganography is a method of hiding secret message in other innocuous looking object so that its presence is not revealed. In this paper, a message, which is a computer file of any type and size, is hidden in a selected cover or carrier, which is a computer file of certain types. The steganography method used in this paper is called append insertion steganography method. This method is chosen as an attempt to remove the limitation of message format, which appears in many popular steganography methods. To scramble the meaning of the hidden message, AES-256 (Rijndael algorithm) is used to encrypt the message with a secret passphrase. A special block of bytes is used to identify and verify the original message so it can be recovered while retaining its integrity. The C# programming language and .NET Framework are chosen to implement the algorithm into a Windows application. In this paper, one cover file contains exactly one message file. In the testing, five random files are used as secret message. Their integrity is calculated using SHA-256 before hiding and after recovery. In the testing, they all retain their integrity, proven by exact hash values. Thus, the application as the implementation of proposed algorithm is proven feasible but only for personal use as some improvements still have to be implemented.

Uncertainty-driven nuclear data evaluation including thermal (n,α) applied to 59Ni

This paper presents a novel approach to the evaluation of nuclear data (ND), combining experimental data for thermal cross sections with resonance parameters and nuclear reaction modeling. The method involves sampling of various uncertain parameters, in particular uncertain components in experimental setups, and provides extensive covariance information, including consistent cross-channel correlations over the whole energy spectrum. The method is developed for, and applied to, 59Ni, but may be used as a whole, or in part, for other nuclides.59Ni is particularly interesting since a substantial amount of 59Ni is produced in thermal nuclear reactors by neutron capture in 58Ni and since it has a non-threshold (n,α) cross section. Therefore, 59Ni gives a very important contribution to the helium production in stainless steel in a thermal reactor. However, current evaluated ND libraries contain old information for 59Ni, without any uncertainty information.The work includes a study of thermal cross section experiments and a novel combination of this experimental information, giving the full multivariate distribution of the thermal cross sections. In particular, the thermal (n,α) cross section is found to be 12.7±.7 b. This is consistent with, but yet different from, current established values.Further, the distribution of thermal cross sections is combined with reported resonance parameters, and with TENDL-2015 data, to provide full random ENDF files; all of this is done in a novel way, keeping uncertainties and correlations in mind. The random files are also condensed into one single ENDF file with covariance information, which is now part of a beta version of JEFF 3.3.Finally, the random ENDF files have been processed and used in an MCNP model to study the helium production in stainless steel. The increase in the (n,α) rate due to 59Ni compared to fresh stainless steel is found to be a factor of 5.2 at a certain time in the reactor vessel, with a relative uncertainty due to the 59Ni data of 5.4%.

A Precise Design for Testing High-Speed Embedded Memory using a BIST Circuit

ABSTRACT Built-in self-test (BIST) mechanism has been a very important approach for testing embedded memory's function and performance. In this paper, a high-speed BIST design for embedded static random access memory (SRAM) and one-port register file (RF) IPs testing was presented. With the purpose of achieving high-speed requirement, the pipe-line strategy is adopted in BIST circuit. Four SRAM instances and four one-port RF instances with the BIST circuit are integrated in a test chip. And the test chip has been fabricated in 28 nm low-leakage logical process. The final silicon data indicated that the proposed implementation is efficient and reliable for memory testing. Furthermore, the test result also show that the yield of memory instances with BIST circuits in the test chip reached up to nearly 100%.

Isotope

Existing storage stacks are top heavy and expect little from block storage. As a result, new high-level storage abstractions—and new designs for existing abstractions—are difficult to realize, requiring developers to implement from scratch complex functionality such as failure atomicity and fine-grained concurrency control. In this article, we argue that pushing transactional isolation into the block store (in addition to atomicity and durability) is both viable and broadly useful, resulting in simpler high-level storage systems that provide strong semantics without sacrificing performance. We present Isotope, a new block store that supports ACID transactions over block reads and writes. Internally, Isotope uses a new multiversion concurrency control protocol that exploits fine-grained, subblock parallelism in workloads and offers both strict serializability and snapshot isolation guarantees. We implemented several high-level storage systems over Isotope, including two key-value stores that implement the LevelDB API over a hash table and B-tree, respectively, and a POSIX file system. We show that Isotope’s block-level transactions enable systems that are simple (100s of lines of code), robust (i.e., providing ACID guarantees), and fast (e.g., 415MB/s for random file writes). We also show that these systems can be composed using Isotope, providing applications with transactions across different high-level constructs such as files, directories, and key-value pairs.

Covariances for the 56Fe radiation damage cross sections

The energy-energy and reaction-reaction covariance matrices were calculated for the n + 56 Fe damage cross-sections by Total Monte Carlo method using the TENDL-2013 random files. They were represented in the ENDF-6 format and added to the unperturbed evaluation file. The uncertainties for the spectrum averaged radiation quantities in the representative fission, fusion and spallation facilities were first time assessed as 5–25%. Additional 5 to 20% have to be added to the atom displacement rate uncertainties to account for accuracy of the primary defects simulation in materials. The reaction-reaction correlation were shown to be 1% or less.