Comparing Successful DLT Consortia: A Lifecycle Perspective

In 2021, enterprise distributed ledger technology has evolved beyond the proof-of-concept stage. It is now providing business value to large consortia in several successful and well documented case studies. Nevertheless, other consortia and initiatives are stuck in early stages of consortium formation or conceptualization. They stand to benefit from lessons learned by successful consortia, but an in-depth comparison has not yet been conducted. Thus, this study performs the first methodological comparison of large DLT consortia that have launched a product. Based on the temporal evolution of these consortia, a lifecycle with 4 stages and 12 sub-phases is developed to provide further guidance for early-stage consortia. The results show how 9 pioneer consortia have successfully integrated novel DLT into existing processes, but also point out challenges faced on the way

Analysis of possibilities to increase oil recovery with the use of nitrogen in the context of deep oil deposits of the Dnipro-Donetsk oil-and-gas Ukrainian province

Purpose is to increase oil recovery of deep oil deposits of the Dnipro-Donetsk oil-and-gas Ukrainian province with the use of nitrogen. Methods. Experiments, intended to residual oil displacement with the use of different driving agents, involved laboratory modeling of the process when a seam was simulated as such being close maximally to a real seam and samples of formation fluids were applied. The experiments, which materialized equilibrium displacement (without mass transfer), used seam models developed from cores of V-19n seam (Perekopivske deposit). 43 core samples were analyzed with 3.3 – 226.0·10-3 µm2 permeability. Findings. Characteristics and applicability of nitrogen and flue gas to increase oil recovery have been analyzed. Theoretic prerequisites of the mechanism, aimed at oil displacement using nitrogen and flue gases, have been formulated. Results of the laboratory experiments of oil displacement by means of nitrogen within a porous environment have helped determine that minimum pressure of mutual oil and nitrogen dissolution is 36.0 – 38.0 MPa. In terms of mutual mixing of agents at 110 – 112°С temperature, 36.4 МPа gas injection pressure, and nitrogen pumping velocity being 1 cm3 per 40 minutes, oil displacement ratio achieved 0.76 – 0.78. Originality. For the first time, parameters of mixable oil displacement using nitrogen for the conditions of deep oil deposits of the Dnipro-Donetsk petroleum province in Ukraine have been determined. Efficiency of mixable nitrogen displacement to compare with water displacement and nitrogen displacement under equilibrium conditions has been proved. Practical implications. The advanced technique of nitrogen use to improve oil recovery in the context of deep oil deposits has been proposed. The technique is applicable to extract residual oil from the depleted deposits.Мета. Підвищення нафтовилучення глибоких нафтових родовищ Дніпровсько-Донецької нафтогазоносної провінції України з використанням азоту. Методика. Експериментальні дослідження витіснення залишкової нафти різними витіснювальними агентами проводили шляхом лабораторного моделювання процесу зі створенням зразків пласта, максимально наближених до реального пласту, і використанням зразків пластових флюїдів. В експериментах, в яких реалізувалося рівноважне витіснення (без масопереносу), використовувалися моделі пласта, які споруджувалися з кернового матеріалу пласта В-19н Перекоповського родовища. Було досліджено 43 зразки керна, проникність сягала в межах 3.3 – 226.0·10-3 мкм2. Результати. Проаналізовано особливості та умови застосування азоту й димових газів для підвищення нафтовіддачі пластів. Сформульовано теоретичні передумови механізму витіснення нафти з пласта азотом і димовими газами. Встановлено за результатами лабораторних досліджень витіснення нафти азотом у пористому середовищі мінімальний тиск взаємного розчинення нафти та азоту, котрий становить 36.0 – 38.0 МПа. В умовах взаємного змішування агентів при температурі 110 – 112°С, тиску нагнітання газу 36.4 МПа і швидкості нагнітання азоту 1 см3 за 40 хвилин коефіцієнт витіснення нафти досягав величини 0.76 – 0.78. Наукова новизна. Вперше встановлені параметри змішуваного витіснення нафти азотом для умов глибоких нафтових родовищ Дніпровсько-Донецької нафтогазоносної провінції України. Доведено високу ефективність змішуваного витіснення азотом в порівнянні з витісненням водою і витісненням азотом при рівноважних умовах. Практична значимість. Запропоновано удосконалену технологію використання азоту для підвищення нафтовилучення глибоких нафтових родовищ, яка може бути використана для виснажених нафтових родовищ.Цель. Увеличение нефтеотдачи глубокозалегающих нефтяных месторождений Днепровско-Донецкой нефтегазоносной провинции Украины с использованием азота. Методика. Экспериментальные исследования вытеснения остаточной нефти разными вытесняющими агентами проводили путем лабораторного моделирования процесса с созданием образцов пласта, максимально приближенных к реальному пласту, и использованием образцов пластовых флюидов. В экспериментах, в которых реализовалось равновесное вытеснение (без масопереноса), использовались модели пласта, которые сооружались из кернового материала пласта В-19н Перекоповского месторождения. Были исследованы 43 образца керна, проницаемость находилась в пределах 3.3 – 226.0·10-3 мкм2. Результаты. Проанализированы особенности и условия применения азота и дымовых газов для повышения нефтеотдачи пластов. Сформулированы теоретические предпосылки механизма вытеснения нефти из пласта азотом и дымовыми газами. Установлено по результатам лабораторных исследований вытеснения нефти азотом в пористой среде минимальное давление взаимного растворения нефти и азота, которое составляет 36.0 – 38.0 МПа. В условиях взаимного смешивания агентов при температуре 110 – 112°С, давлении нагнетания газа 36.4 МПа и скорости нагнетания азота 1 см3 за 40 минут коэффициент вытеснения нефти достигал величины 0.76 – 0.78. Научная новизна. Впервые установлены параметры смешиваемого вытеснения нефти азотом для условий глубокозалегающих нефтяных месторождений Днепровско-Донецкой нефтегазоносной провинции Украины. Доказана высокая эффективность смешиваемого вытеснения азотом по сравнению с вытеснением водой и вытеснением азотом при равновесных условиях. Практическая значимость. Предложена усовершенствованная технология использования азота для повышения нефтеотдачи глубокозалегающих нефтяных месторождений, которая может быть использована для истощенных нефтяных месторождений.The research results have been obtained with no support in the form of grants of projects. The authors express thanks to PJSC “Ukrnafta” for the possibility to carry out the experiments, which findings are represented by the paper, on the basis of Scientific-Research and Design Institute PJSC “Ukrnafta”

Detecting Blockchain Security Threats

In many organizations, permissioned blockchain networks are currently transitioning from a proof-of-concept stage to production use. A crucial part of this transition is ensuring awareness of potential threats to network operations. Due to the plethora of software components involved in distributed ledgers, threats may be difficult or impossible to detect without a structured monitoring approach. To this end, we conduct a survey of attacks on permissioned blockchains and develop a set of threat indicators. To gather these indicators, a data processing pipeline is proposed to aggregate log information from relevant blockchain components, enriched with data from external sources. To evaluate the feasibility of monitoring current blockchain frameworks, we determine relevant data sources in Hyperledger Fabric. Our results show that the required data is mostly available, but also highlight significant improvement potential with regard to threat intelligence, chaincode scanners and built-in metrics

Towards case-based medical learning in radiological decision making using content-based image retrieval

<p>Abstract</p> <p>Background</p> <p>Radiologists' training is based on intensive practice and can be improved with the use of diagnostic training systems. However, existing systems typically require laboriously prepared training cases and lack integration into the clinical environment with a proper learning scenario. Consequently, diagnostic training systems advancing decision-making skills are not well established in radiological education.</p> <p>Methods</p> <p>We investigated didactic concepts and appraised methods appropriate to the radiology domain, as follows: (i) Adult learning theories stress the importance of work-related practice gained in a team of problem-solvers; (ii) Case-based reasoning (CBR) parallels the human problem-solving process; (iii) Content-based image retrieval (CBIR) can be useful for computer-aided diagnosis (CAD). To overcome the known drawbacks of existing learning systems, we developed the concept of image-based case retrieval for radiological education (IBCR-RE). The IBCR-RE diagnostic training is embedded into a didactic framework based on the Seven Jump approach, which is well established in problem-based learning (PBL). In order to provide a learning environment that is as similar as possible to radiological practice, we have analysed the radiological workflow and environment.</p> <p>Results</p> <p>We mapped the IBCR-RE diagnostic training approach into the Image Retrieval in Medical Applications (IRMA) framework, resulting in the proposed concept of the IRMAdiag training application. IRMAdiag makes use of the modular structure of IRMA and comprises (i) the IRMA core, i.e., the IRMA CBIR engine; and (ii) the IRMAcon viewer. We propose embedding IRMAdiag into hospital information technology (IT) infrastructure using the standard protocols Digital Imaging and Communications in Medicine (DICOM) and Health Level Seven (HL7). Furthermore, we present a case description and a scheme of planned evaluations to comprehensively assess the system.</p> <p>Conclusions</p> <p>The IBCR-RE paradigm incorporates a novel combination of essential aspects of diagnostic learning in radiology: (i) Provision of work-relevant experiences in a training environment integrated into the radiologist's working context; (ii) Up-to-date training cases that do not require cumbersome preparation because they are provided by routinely generated electronic medical records; (iii) Support of the way adults learn while remaining suitable for the patient- and problem-oriented nature of medicine. Future work will address unanswered questions to complete the implementation of the IRMAdiag trainer.</p

A Distributed Ledger Approach to Digital Twin Secure Data Sharing

The Digital Twin refers to a digital representation of any real-world counterpart allowing its management (from simple monitoring to autonomy). At the core of the concept lies the inclusion of the entire asset lifecycle. To enable all lifecycle parties to partake, the Digital Twin should provide a sharable data base. Thereby, integrity and confidentiality issues are pressing, turning security into a major requirement. However, given that the Digital Twin paradigm is still at an early stage, most works do not consider security yet. Distributed ledgers provide a novel technology for multi-party data sharing that emphasizes security features such as integrity. For this reason, we examine the applicability of distributed ledgers to secure Digital Twin data sharing. We contribute to current literature by identifying requirements for Digital Twin data sharing in order to overcome current infrastructural challenges. We furthermore propose a framework for secure Digital Twin data sharing based on Distributed Ledger Technology. A conclusive use case demonstrates requirements fulfillment and is followed by a critical discussion proposing avenues for future work

BISCUIT - Blockchain Security Incident Reporting based on Human Observations

Security incidents in blockchain-based systems are frequent nowadays, which calls for more structured efforts in incident reporting and response. To improve the current status quo of reporting incidents on blogs and social media, we propose a decentralized incident reporting and discussion system. Our approach guides users (security novices) towards a classification of their observations using a tiered taxonomy of blockchain incidents. Questions based on previous incidents interactively support the classification. Post submission a security incident response committee then discusses these observations on our decentralized platform to decide on an appropriate response. For evaluation, we implement our model as a decentralized application and demonstrate its practical suitability in a preliminary user study

Trapdoor Memory-Hard Functions

Memory-hard functions (MHF) are functions whose evaluation provably requires a lot of memory. While MHFs are an unkeyed primitive, it is natural to consider the notion of trapdoor MHFs (TMHFs). A TMHF is like an MHF, but when sampling the public parameters one also samples a trapdoor which allows evaluating the function much cheaper. Biryukov and Perrin (Asiacrypt\u2717) were the first to consider TMHFs and put forth a candidate TMHF construction called Diodon that is based on the Scrypt MHF (Percival, BSDCan\u2709). To allow for a trapdoor, Scrypt\u27s initial hash chain is replaced by a sequence of squares in a group of unknown order where the order of the group is the trapdoor. For a length $n$ sequence of squares and a group of order $N$, Diodon\u27s cumulative memory complexity (CMC) is $O(n^2\log N)$ without the trapdoor and $O(n \log(n) \log(N)^2)$ with knowledge of it. While Scrypt is proven to be optimally memory-hard in the random oracle model (Alwen et al., Eurocrypt\u2717), Diodon\u27s memory-hardness has not been proven so far. In this work, we fill this gap by rigorously analyzing a specific instantiation of Diodon. We show that its CMC is lower bounded by $\Omega(\frac{n^2}{\log n} \log N)$ which almost matches the upper bound. Our proof is based Alwen et al.\u27s lower bound on Scrypt\u27s CMC but requires non-trivial modifications due to the algebraic structure of Diodon. Most importantly, our analysis involves a more elaborate compression argument and a solvability criterion for certain systems of Diophantine equations

Damage Location in Mechanical Structures by Multi-Objective Pattern Search

We propose a multi-objective global pattern search algorithm for the task of locating and quantifying damage in flexible mechanical structures. This is achieved by identifying eigenfrequencies and eigenmodes from measurements and matching them against the results of a finite element simulation model, which leads to a nonsmooth nonlinear bi-objective parameter estimation problem. A derivative-free optimization algorithm is required since the problem is nonsmooth and also because complex mechanical simulation models are often solved using commercial black-box software. Moreover, the entire set of non-dominated solutions is of interest to practitioners. Most solution approaches published to date are based on meta-heuristics such as genetic algorithms. The proposed multi-objective pattern-search algorithm provides a mathematically well-founded alternative. It features a novel sorting procedure that reduces the complexity in our context. Test runs on two experimental structures with multiple damage scenarios are used to validate the approach. The results demonstrate that the proposed algorithm yields accurate damage locations and requires moderate computational resources. From the engineer's perspective it represents a promising tool for structural health monitoring

Performance Testing of a Novel Off-plane Reflection Grating and Silicon Pore Optic Spectrograph at PANTER

An X-ray spectrograph consisting of radially ruled off-plane reflection gratings and silicon pore optics was tested at the Max Planck Institute for extraterrestrial Physics PANTER X-ray test facility. The silicon pore optic (SPO) stack used is a test module for the Arcus small explorer mission, which will also feature aligned off-plane reflection gratings. This test is the first time two off-plane gratings were actively aligned to each other and with a SPO to produce an overlapped spectrum. The gratings were aligned using an active alignment module which allows for the independent manipulation of subsequent gratings to a reference grating in three degrees of freedom using picomotor actuators which are controllable external to the test chamber. We report the line spread functions of the spectrograph and the actively aligned gratings, and plans for future development.Comment: Draft Version March 19, 201