scholarly journals The security of the BLT signature scheme with practical implementation issues

2022 ◽  
Vol 2 (14) ◽  
pp. 35-44
Author(s):  
Triệu Quang Phong ◽  
Võ Tùng Linh
Keyword(s):  
Theoretical Model ◽  
Practical Implementation ◽  
Signature Scheme ◽  
Timing Information

Abstract—KSI infrastructure is a time-stamping and server-based signature solution deployed in Estonia to provide the integrity and timing information of data. With the goal of providing a personal signature that does not depend on the long-term secrecy of signing keys, Buldas et al. have proposed a BLT scheme that is based on the KSI infrastructure. Although Buldas et al. have shown that the (modified) BLT scheme is secure in the theoretical model, the fact that its practical implementation does not follow that description. In this paper, we will evaluate and provide two attack scenarios if the BLT schema is implemented in such a way, and then propose a solution to that problem. Tóm tắt—Hạ tầng KSI là một giải pháp chữ ký dựa trên máy chủ chứa thông tin thời gian được thử nghiệm triển khai ở Estonia để cung cấp tính toàn vẹn và thông tin về thời gian của dữ liệu.Với mục tiêu tạo ra một chữ ký số cá nhân mà không phụ thuộc vào tính bí mật lâu dài của các khóa ký, Buldas và các cộng sự đã đề xuất lược đồ BLT dựa trên nền của hạ tầng KSI. Mặc dù, Buldas và các cộng sự đã chỉ ra rằng lược đồ BLT (sửa đổi) là an toàn trong mô hình lý thuyết, nhưng triển khai thực tế của lược đồ này không hoàn toàn tuân theo mô tả đó. Trong bài báo này, chúng tôi sẽ đánh giá và đưa ra hai kịch bản tấn công nếu lược đồ BLT được triển khai như vậy, và sau đó đề xuất một giải pháp cho vấn đề đó.

scholarly journals The reputation trap of NGO accountability

2015 ◽  
Vol 7 (3) ◽  
pp. 426-463 ◽  
Author(s):  
Stephen E. Gent ◽  
Mark J. C. Crescenzi ◽  
Elizabeth J. Menninga ◽  
Lindsay Reid
Keyword(s):  
Theoretical Model ◽  
Unintended Consequences ◽  
International Crisis ◽  
Governmental Organizations ◽  
Non Governmental Organizations ◽  
Policy Goals ◽  
Ngo Accountability ◽  
The Relationship

Can concerns for one’s reputation cause non-governmental organizations (NGOs) to alter their behavior to the detriment of achieving their policy goals? To answer this question, we explore the relationship between NGOs and their donors. Our theoretical model reveals that reputation can be a key piece of information in the decision to fund an NGO’s activities. Reputation can become so important to the NGO’s survival that it interferes with the long-term policy goals of the organization. As such, reputations can become a double-edged sword, simultaneously providing the information donors seek while constraining NGOs from realizing policy goals. We apply this logic to the problem of NGO accountability, which has received increasing attention in recent years, and demonstrate that the tools used by donors to improve accountability can trigger unintended consequences. We illustrate this strategic dynamic with two types of NGO activity: water improvement and international crisis mediation.

A Model for Working with the Elderly in Institutions

1981 ◽  
Vol 62 (7) ◽  
pp. 420-425 ◽  
Author(s):  
Alicia S. Cook
Keyword(s):  
Theoretical Model ◽  
Long Term Care ◽  
The Elderly ◽  
Term Care ◽  
Human Needs

Abraham Maslow's hierarchy of human needs provides a useful operating framework for professionals working with residents of long-term care institutions. The difficulties and obstacles that the elderly often encounter in these facilities are addressed and discussed for each level of the theoretical model.

scholarly journals On the Statistical Reflection of Long-Term Growth in Agricultural Production

2020 ◽  
Vol 27 (5) ◽  
pp. 36-47
Author(s):  
D. S. Ternovsky ◽  
V. Ya. Uzun
Keyword(s):  
Theoretical Model ◽  
Agricultural Production ◽  
Crop Production ◽  
Complex Structure ◽  
Livestock Production ◽  
Chain Indices ◽  
Statistical Reflection ◽  
The Relationship ◽  
Constant Prices

The article presents the results of a study aimed at proving the existence of systematic error in traditional calculations of long-term growth rates of agricultural production based on chain indices of agricultural production. According to the authors, the article also introduces a more accurate assessment of its dynamics with the account to the structure of the relationship between prices and the volume of agricultural production. The paper describes a theoretical model that is a methodological basis for the study and explains the discrepancy in assessing the dynamics of agricultural production using chain indices and indexes at constant prices. It allows establishing differences in the ratios of the Laspeyres, Paasche, and Lowe indices for crop and livestock production, due to factors in the formation of demand and the complex structure of the relationship between the price level and the volume of production. The adequacy of the constructed theoretical model is proved based on aggregated data that eliminated the influence of incompleteness of the initial information. As a result, it was established that livestock production is characterized by time-distributed changes in prices and quantity of products, which makes it possible to assess its dynamics using both chain indices and symmetric indices. It is proved that the dynamics of crop production cannot be adequately described using chain indices, since a positive correlation of prices of the previous period and production volumes of the current period causes an overstatement of the index in comparable prices of the previous year. Based on calculations within the proposed aggregated model, it is proved that the use of constant prices as the Lowe index weights, updated every five years, is an acceptable approximation of the Fisher symmetric index. Application of the indicated methodology for calculating the index to the data on Russian agricultural production by main types of products in 1990-2018 allowed to establish an overstatement of dynamics by 11.9%. The main difference falls on crop production (+ 19.6%), while for livestock - the differences are insignificant (-0.7%).

scholarly journals Theoretical and Experimental Study on the Antisliding Performance of Casting Steel Cable Clamps

2019 ◽  
Vol 2019 ◽  
pp. 1-18 ◽  
Author(s):  
Yangjie Ruan ◽  
Bin Luo ◽  
Mingmin Ding ◽  
Lifan Huang ◽  
Zhengxing Guo
Keyword(s):  
Theoretical Model ◽  
Transversely Isotropic ◽  
High Strength ◽  
Clamping Force ◽  
Steel Cable ◽  
Cable Tension ◽  
Bolt Preload ◽  
Term Creep ◽  
Casting Steel

For large-span cable structures, a cable clamp is a key joint that connects adjacent structural components. In general, the antisliding performance of cable clamps determines their resistance capacity, and the antisliding force is generated by the clamping force induced by the high-strength bolts and the contact surfaces between the cable and the clamp. Since the existing methods are not sufficiently comprehensive for use to predict the precise bolt preload, a theoretical model developed by considering transversely isotropic material and the generalized Hook’s law is presented to predict the attenuation values of the bolt clamping force and the corresponding parameters. Then, to meet the requirements of Eurocode 3, a new laboratory test is performed to reveal the antisliding mechanism of cable clamps, considering the effects of long-term creep and cable tension. According to the results of the data collected by real-time monitoring, the actual ultimate antisliding force of the clamp and the comprehensive friction coefficient are determined. Finally, a comparative study between the theoretical results and the experimental results is conducted. The proposed theoretical model can predict the actual attenuation of the bolt clamping force after cable tension. The results show that the stiffness of the clamp plate should be minimized when designing the clamp to reduce the loss of the bolt preload.

Nine steps towards a better water meter management

2012 ◽  
Vol 65 (7) ◽  
pp. 1273-1280 ◽  
Author(s):  
F. J. Arregui ◽  
J. Soriano ◽  
E. Cabrera ◽  
R. Cobacho
Keyword(s):  
Field Work ◽  
Laboratory Work ◽  
Practical Implementation ◽  
Water Meters ◽  
Term Management ◽  
Critical Aspects ◽  
Water Meter

The paper provides a comprehensive perspective of the critical aspects to be taken into account when planning the long-term management of water meters in a utility. In order to facilitate their quick understanding and practical implementation, they have been structured into nine steps. Ranging from an initial audit up to the final periodic meter replacement planning, these steps cover three aspects of the problem – field work, laboratory work and management tasks; and each one is developed in detail paying attention to the particular data needed and noting the practical outcome it will yield.

A Bayesian Machine Learning Approach for Efficient Integrity Management of Steel Lazy Wave Risers

2020 ◽  
Author(s):  
Rasoul Hejazi ◽  
Andrew Grime ◽  
Mark Randolph ◽  
Mike Efthymiou
Keyword(s):  
Machine Learning ◽  
Fatigue Failure ◽  
Learning Process ◽  
Predictive Models ◽  
Structural Integrity ◽  
Degradation Mechanism ◽  
Data Driven ◽  
Practical Implementation ◽  
Integrity Management

Abstract In-service integrity management (IM) of steel lazy wave risers (SLWRs) can benefit significantly from quantitative assessment of the overall risk of system failure as it can provide an effective tool for decision making. SLWRs are prone to fatigue failure within their touchdown zone (TDZ). This failure mode needs to be evaluated rigorously in riser IM processes because fatigue is an ongoing degradation mechanism threatening the structural integrity of risers throughout their service life. However, accurately evaluating the probability of fatigue failure for riser systems within a useful time frame is challenging due to the need to run a large number of nonlinear, dynamic numerical time domain simulations. Applying the Bayesian framework for machine learning, through the use of Gaussian Processes (GP) for regression, offers an attractive solution to overcome the burden of prohibitive simulation run times. GPs are stochastic, data-driven predictive models which incorporate the underlying physics of the problem in the learning process, and facilitate rapid probabilistic assessments with limited loss in accuracy. This paper proposes an efficient framework for practical implementation of a GP to create predictive models for the estimation of fatigue responses at SLWR hotspots. Such models are able to perform stochastic response prediction within a few milliseconds, thus enabling rapid prediction of the probability of SLWR fatigue failure. A realistic North West Shelf (NWS) case study is used to demonstrate the framework, comprising a 20” SLWR connected to a representative floating facility located in 950 m water depth. A full hindcast metocean dataset with associated statistical distributions are used for the riser long-term fatigue loading conditions. Numerical simulation and sampling techniques are adopted to generate a simulation-based dataset for training the data-driven model. In addition, a recently developed dimensionality reduction technique is employed to improve efficiency and reduce complexity of the learning process. The results show that the stochastic predictive models developed by the suggested framework can predict the long-term TDZ fatigue damage of SLWRs due to vessel motions with an acceptable level of accuracy for practical purposes.

Toward a Psychology of Singlehood: An Attachment-Theory Perspective on Long-Term Singlehood

2018 ◽  
Vol 27 (5) ◽  
pp. 324-331 ◽  
Author(s):  
Christopher A. Pepping ◽  
Geoff MacDonald ◽  
Penelope J. Davis
Keyword(s):  
Theoretical Model ◽  
Attachment Theory ◽  
Empirical Evidence ◽  
Psychological Theory ◽  
Heterogeneous Group ◽  
Scientific Study ◽  
Western World ◽  
Future Research ◽  
Personal Choice

The number of people who remain single for long periods of time is sizeable and growing in the Western world, yet they are largely ignored in psychological theory and research. In this article, we review psychological and sociological evidence that long-term singles are a heterogeneous group of individuals, outline an attachment-theoretical model of long-term singlehood, and review direct and indirect empirical evidence suggestive of at least three distinct subgroups of long-term singles: (a) singlehood due to attachment-system deactivation, (b) singlehood due to attachment-system hyperactivation, and (c) singlehood as a secure personal choice. Our aim is to highlight long-term singles as a population that merits scientific study and to provide a foundation on which future research can build.

scholarly journals Numerical Analysis of Deflections of Multi-Layered Beams

2015 ◽  
Vol 15 (4) ◽  
pp. 33-42
Author(s):  
Tadeusz Biliński ◽  
Tomasz Socha
Keyword(s):  
Theoretical Model ◽  
Numerical Analysis ◽  
Wood Structures ◽  
User Subroutine ◽  
Layered Beams ◽  
Linear Viscoelastic ◽  
Laboratory Investigations ◽  
Term Response ◽  
Good Agreement

Abstract The paper concerns the rheological bending problem of wooden beams reinforced with embedded composite bars. A theoretical model of the behaviour of a multi-layered beam is presented. The component materials of this beam are described with equations for the linear viscoelastic five-parameter rheological model. Two numerical analysis methods for the long-term response of wood structures are presented. The first method has been developed with SCILAB software. The second one has been developed with the finite element calculation software ABAQUS and user subroutine UMAT. Laboratory investigations were conducted on sample beams of natural dimensions in order to validate the proposed theoretical model and verify numerical simulations. Good agreement between experimental measurements and numerical results is observed.

Differential Surface Plasmon Resonance Sensor for the Detection of Chemicals and Biochemicals

2013 ◽  
Vol 543 ◽  
pp. 310-313 ◽  
Author(s):  
Carmelo Fallauto ◽  
Guido Perrone ◽  
Alberto Vallan
Keyword(s):  
Surface Plasmon Resonance ◽  
Surface Plasmon ◽  
Plasmon Resonance ◽  
High Sensitivity ◽  
Practical Implementation ◽  
Resonance Sensor ◽  
Order Of Magnitude ◽  
Long Term Monitoring ◽  
Term Monitoring

Surface plasmon resonance is one the most common optical sensing techniques for the detection of chemicals and biochemicals, although still mainly confined to lab applications. Typically, these sensors are made by a thin gold layer deposited on a glass prism or on an optical fiber similar to those used in telecom applications. Key advantages of this technique are the possibility to specifically detect different chemicals through functionalization of the metal surface and the high sensitivity, although the latter may turn into a weakness in long term monitoring applications due to cross-sensitivity to parasitic effects. To overcome this limitation the paper proposes a novel sensor implementation with a cascaded double sensing area, particularly suited for long term monitoring of pollutant since one sensing area is actually used to detect the desired molecules, while the other for compensating drifts due to fluctuations, misalignments and temperature variations. The paper addresses mainly the prism-based implementation, but the proposed configuration is suited also for an all-fiber approach. Examples of practical implementation of the proposed techniques are given, evidencing an accuracy improvement of more than an order of magnitude.

scholarly journals Risk profiles and corporate social responsibility for socially disadvantaged groups

2017 ◽  
Vol 11 (1) ◽  
pp. 863-874
Author(s):  
Cosmin Serbanescu ◽  
Adrian Vintilescu-Belciug ◽  
Lacramioara Corches
Keyword(s):  
Corporate Social Responsibility ◽  
Theoretical Model ◽  
Social Responsibility ◽  
Risk Profile ◽  
Risk Level ◽  
Practical Implementation ◽  
Risk Profiles ◽  
Social Risks ◽  
Corporate Social ◽  
The Impact

Abstract Developing a suitable mechanism to stimulate the effective redeployment of capital to social activities can be designed using the corporate social responsibility (CSR) concept. Informational asymmetry about the real state of social risks influences the effectiveness of allocations in social protection. Reducing information asymmetries can be achieved by providing the corporations with socially determined risk profiles based on predetermined patterns. Offering concrete lines of action following the risk profiles approach which to base investment decisions of companies in CSR can maximize the results of such a mechanism. In a previous study the authors have developed a theoretical model for determining the poverty risk profile. This study aims to present the practical application of the theoretical model and to provide comments on some errors. Hence, the authors analyzed Buzau county municipalities in presenting the highest risk level determined by the theoretical model and related causes and performed an impact assessment of an investment in CSR based on a model. Specifically, the authors evaluated the impact of reducing the risk of poverty for a suitable investment in CSR. In the second part of the study, the authors analyzed the types of errors that can be found in the municipalities risk profile model due to the granularity of the data. Thus, for the error of over-inclusion, the authors assessed social allocative efficiency at the community level using benchmarking analysis, Data Envelopment respectively and analyzed the data of the under-inclusion error in Buzau county villages. The paper aims to analyze the relative limits on quantitative models and risk of poverty and the practical implementation of these types of models in the development of corporate social responsibility. The study provides also a useful tool which can be made available to companies in order to increase the vulnerable groups’ life quality and the satisfaction of shareholders, stakeholders and related parties following redeployments according to specific CSR mechanisms.

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